Monoclonal antibodies against nkg2a

ABSTRACT

The present invention relates to methods of treating immune disorders, particularly autoimmune or inflammatory disorders, and methods of producing antibodies and other compounds for use in therapeutic strategies for treating such disorders. Generally, the present methods involve the use of antibodies or other compounds that prevent the stimulation of NKG2A receptors on NK cells, leading to the lysis of dendritic cells that contribute to the pathology of the disorders.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 14/594,353, filed Jan.12, 2015, now U.S. Pat. No. 10,160,810, which is a divisional of U.S.Ser. No. 11/720,553, filed May 31, 2007, now U.S. Pat. No. 8,993,319,which is the U.S. national stage application of International PatentApplication No. PCT/M2005/004013, filed Dec. 27, 2005, which claims thebenefit of U.S. Provisional Patent Application No. 60/639,465, filedDec. 28, 2004, and U.S. Provisional Patent Application No. 60/639,832,filed Dec. 28, 2004, the disclosures of which are hereby incorporated byreference in their entireties, including all figures, tables and aminoacid or nucleic acid sequences.

FIELD OF THE INVENTION

The present invention relates to monoclonal antibodies and fragmentsthereof directed against the NK cell surface receptor NKG2A, as well asto methods of producing and evaluating such antibodies. The monoclonalantibodies and fragments thereof are useful in treating immunedisorders, particularly autoimmune disorders, as well as other diseasesrequiring modulated NK cell function. Generally, the present methodsinvolve the use of the antibodies and fragments thereof to prevent thestimulation of NKG2A receptors on NK cells, leading to the lysis ofHLA-E or Qa1^(b) expressing cells, such as dendritic cells or activatedT cells, that contribute to the pathology of the disorders to betreated.

BACKGROUND

Maintaining effective immune surveillance without provoking autoimmunereactions requires the precise titration of effector T cell responses.Autoimmune disorders arise when the immune system mounts an immuneresponse against self-antigens (see, e.g., Ludewig et al. (1999) ImmunolRev. 169:45-54). While the mechanisms involved in the triggering andmaintenance of autoimmune reactions is unclear, it is likely that theappearance of previously immunologically ignored antigens in secondarylymphoid organs is involved.

Dendritic cells are bone-marrow derived antigen presenting cells (APCs)that play a key role in the immune response (see, e.g., O'Neill et al.(2004) Blood 104:2235-2246). DCs internalize bacteria, viruses, dyingcells, and various complex molecules through phagocytosis, endocytosis,and pinocytosis. Incorporated proteins are broken down into peptides,which are then presented on the DC cell surface along with MHC class Iand class II molecules. Antigens loaded onto MHC class I are typicallyderived from endogenous proteins and are recognized by CD8+ T cells,whereas MHC class II loaded antigens are generally derived from externalproteins and are recognized by CD4+ T cells. Following antigen capture,immature DC cells mature to form mature DCs which show reducedphagocytosis, migrate to lymphoid tissues, and have enhanced T cellstimulation capacity.

In lymphoid tissues, DCs prime naïve T cells, stimulating their clonalexpansion and differentiation, and can also interact with B cells andcells of the innate immune system, including NK cells. Activated NKcells can kill immature, but not mature, DC cells. As antigen transportand primary sensitization of T lymphocytes is mainly mediated by antigenpresenting dendritic cells, it is likely that the inappropriatepresentation of self antigens by dendritic cells contributes at least inpart to autoimmune disorders.

Natural killer (NK) cells are a subpopulation of lymphocytes involved innon-conventional immunity. NK cells provide an efficientimmunosurveillance mechanism by which undesired cells such as tumor orvirally-infected cells can be eliminated. NK cell activity is regulatedby a complex mechanism that involves both activating and inhibitorysignals (see, e.g., Moretta et al. (2001) Annu Rev Immunol 19:197-223;Moretta et al. (2003) EMBO J EPub December 18; Ravetch et al. (2000)Science 290:84-89; Zambello et al. (2003) Blood 102:1797-805; Moretta etal. (1997) Curr Opin Immunol 9:694-701; the entire disclosures of whichare herein incorporated by reference).

Several distinct NK-specific receptors have been identified that playimportant roles in the NK cell mediated recognition and killing of HLAClass I deficient target cells. These receptors, termed NKp30, NKp46 andNKp44, are members of the Ig superfamily. Their cross-linking, inducedby specific mAbs, leads to a strong NK cell activation resulting inincreased intracellular Ca⁺⁺ levels, triggering of cytotoxicity, andlymphokine release. Importantly, mAb-mediated activation of NKp30,NKp46, and/or NKp44 results in an activation of NK cytotoxicity againstmany types of target cells. These findings provide evidence for acentral role of these receptors in natural cytotoxicity.

NK cells are negatively regulated by major histocompatibility complex(MHC) class I-specific inhibitory receptors (Karre et al. (1986) Nature319:675-8; Ohlen et al, (1989) Science 246:666-8). These specificreceptors bind to polymorphic determinants of major histocompatibilitycomplex (MHC) class I molecules or HLA and inhibit natural killer (NK)cell lysis. In humans, certain members of a family of receptors termedkiller Ig-like receptors (KIRs) recognize groups of HLA class I alleles(see, e.g., Yawata et al. (2002) Crit Rev Immunol 22:463-82; Martin etal. (2000) Immunogenetics. 51:268-80; Lanier (1998) Annu Rev Immunol.16:359-93; the entire disclosures of which are herein incorporated byreference).

Another important inhibitory receptor on NK cells is CD94-NKG2A, whichinteracts with the non-classical MHC class 1 molecule HLA-E (see, e.g.,Braud et al. (1998) Nature 391:795-799; Lee et al. (1998) PNAS95:5199-5204; Vance et al. (2002) PNAS 99:868-873; Brooks et al. (1999)J Immunol 162:305-313; Miller et al. J Immunol (2003) 171:1369-75;Brooks et al. (1997) J Exp Med 185:795-800; Van Beneden et al. (2001)4302-4311; U.S. patent application no. 20030095965; the entiredisclosures of each of which are herein incorporated by reference). Someof these receptors have the capacity to modulate thresholds of T cellantigen receptor-dependent T cell activation. In the rare absence ofinhibitory receptors, the activating isoforms may augment T celleffector functions and contribute to autoimmune pathology. The aminoacid sequence of NKG2A varies among mammals, including among primates.For example, the human and rhesus monkey versions of the NKG2A proteinsshare less than 90% identity, including approximately 86% within theligand binding domain.

Efforts towards therapeutics for modulating NKG2A, essentially for theprevention of inflammation, have focused on the study of thenonclassical MHC class I molecules, HLA-E for the human receptor andQa-1b for the mouse receptor. For cell surface expression, these MHCmolecules preferentially bind peptides derived from the signal peptidesof other MHC class I molecules. The expression of other class I MHCmolecules can regulate the expression of HLA-E, thereby allowing NKcells to monitor the state of the MHC class I dependent antigenpresentation pathway in potential target cells. The level of cellsurface HLA-E is critical for the NK cell cytotoxicity towards tumor andvirally infected cells. Therapeutic strategies for modulating HLA-Eexpression or function have generally been directed towards using HLA-Ior HSP60 peptides to induce a protective state for the prevention ofinflammation such that NK cells are not activated.

United States patent publication 20030095965 discloses an antibody, 3S9,that binds to NKG2A, NKG2C and NKG2E. 3 S9 purportedly causescross-linking of those receptors and concomitant inhibition of NKcell-mediated lysis. Co-owned PCT patent publication WO 2005/105849discloses the use of an antibody that specifically binds to an NKreceptor, including NKG2A, to treat a patient suffering from NK-typelymphoproliferative disease of granular lymphocytes (NK-LDGL). Suchantibodies inhibit NK cell activity.

Monoclonal antibodies have proven to be enormously useful for thediagnosis and treatment of various diseases. Therapeutic monoclonalantibodies can act through different mechanisms. Some antibodies, suchas Rituxan, recognize antigens (CD20 in the case of Rituxan) present onthe surface of pathological cells, e.g., tumor cells, and act bydirecting the immune system to destroy the recognized cells. Otherantibodies, such as Bexxar, Oncolym, or Zevalin, are coupled toradioisotopes, chemotherapeutic agents, or toxins, leading to the directkilling of cells bound by the antibodies. Still others, such asBasiliximab and Daclizumab (which block IL-2), the IgE blockingOmalizumab, and efaluzimab, act to block the activity of specificproteins. Antibody based therapies are well known in the art and arereviewed, e.g., in Gatto (2004) Curr Med Chem Anti-Canc Agents4(5):411-4, Casadevall et al. (2004) Nat Rev Microbiol. 2(9):695-703,Hinoda et al. (2004) Cancer Sci. 95(8):621-5, Olszewski et al. (2004)Sci STKE. July 06(241):pe30, Coiffier (2004) Hematol J. Suppl 3:S154-8,Roque et al. (2004) Biotechnol Prog. 20(3):639-54, the entiredisclosures of each of which is herein incorporated by reference.

Before antibodies can be used for therapeutic applications in humans, orenter clinical trials, they must go through pre-clinical studies innon-human animals to assess various parameters such as their toxicity,in vivo efficacy, bioavailability, half-life and various otherpharmacokinetic and pharmacodynamic parameters. Such assays aretypically carried out in mammals, and, preferably, where they havebiological activity, i.e. where the mAb is reacting to the homologmolecule in the specie, therefore where one can expect the greatestphysiological similarity to humans. However, studies in nonhumanprimates can be impeded if an antibody directed against a human proteindoes not bind to the nonhuman animal homolog of the target protein. Whencrossreactivity is present, in contrast, not only can the in vivoefficacy of the antibody be tested in the animal, but other issues suchas side effects, toxicity, or kinetic properties that are related to thebinding of the antibody to the target protein can be studied as well.Examples of readily available primates include the New World monkeys andOld World monkeys, such as the cynomolgus monkey (Macaca mulatta), therhesus macaque (Macacus mulatta), the African green monkey (Chlorocebusaethiops), the marmoset (Callithrix jacchus), the saïmiri (Saimirisciureus), all available from “Centre de Primatologie” (CDP: ULP, FortFoch, 67207 Niederhausbergen, France), and the baboon (Papio hamadryas)available from “Station de Primatologie du CNRS”, CD56, 13790Rousset/Arc, France). Chimpanzees and apes in general may also be usedfor testing a candidate medicament, although such instances are rare andgenerally only when no other alternative for testing exists or has beenexhausted.

As antibodies bind to specific 3-dimensional features of their targets,slight changes in the amino acid sequence of a target protein canabolish binding altogether, making it unpredictable whether a givenantibody directed against a protein from one species will also bind tohomologous proteins sharing some but not complete sequence identity.Many instances have been described in which antibodies directed againsta human protein, for example, do not bind to homologs in even closelyrelated species. For example, some antibodies against the human CD4protein do not bind to monkey homologs, even though the human and rhesusmonkey CD4 proteins share close to 94% percent identity (see, e.g.,Genbank IDs GI:116013 and 20981680; Sharma et al. (2000) JPET 293:33-41,2000, the entire disclosures of which are incorporated herein byreference). Other examples include some antibodies against human CD3, awidely pursued pharmaceutical target for antibody development;antibodies, for example UCHT2, otherwise having properties suitable fordevelopment do not crossreact with the monkey CD3 protein.

In view of the prominence and severity of many autoimmune disorders, andthe role of mature dendritic cells in coordinating the immune responseagainst self-antigens, there is a great need in the art for new andeffective therapies that modulate the activity or level of dendriticcells underlying such disorders. Moreover, there is a need for therapiesagainst disorders characterized by aberrant cells (e.g., certain canceror virally infected cells) that are able to shield themselves fromdestruction by the immune system. Finally, there is also a need to finda valid in vivo test system for the therapeutic potential in humans ofmonoclonal antibodies against NKG2A. The present invention addressesthis and other needs.

SUMMARY OF THE INVENTION

The present invention provides monoclonal antibodies and fragmentsthereof directed against the NKG2A receptor. The monoclonal antibodiesand fragments thereof of this invention may either inhibit the abilityof NK cells to lyse normally susceptible target cells (“NK cellinhibitory antibodies”) or reconstitute the ability of NK cells to lyseotherwise protected target cells (“NK cell activating antibodies”). Thefunction of the monoclonal antibodies and fragments thereof of thisinvention is dependent upon their ability to bind to an Fc receptor.

Fc receptors, such as Fc gamma receptors, are expressed on the surfaceof leukocytes. These receptors bind to the Fc portion of immunoglobulin(Ig), e.g. Fc gamma receptors bind to the Fc portion of IgG. Thisbinding helps contribute to immune function by linking the recognitionof antigens by antibodies with cell-based effector mechanisms. Differentimmunoglobulin classes trigger different effector mechanisms through thedifferential interaction of immunoglobulin Fc regions with specific Fcreceptors (FcRs) on immune cells. Activating Fc gamma receptors includeFc gamma RI, Fc gamma RITA, Fc gamma RIIC, and Fc gamma RIII A. Fc gammaRIIB is considered an inhibitory Fc gamma receptor. (For review, see,e.g., Woof et al. (2004) Nat Rev Immunol. 4(2):89-99; Baumann et al.(2003) Arch Immunol Ther Exp (Warsz) 51(6):399-406; Pan et al. (2003)Chin Med J (Engl) 116(4):487-94; Takai et al. (1994) Cell 76:519-529;Ravetch et al. (2001) Annu Rev Immunol 19:275-290, the entiredisclosures of each of which are herein incorporated by reference).

Without being bound by theory, the inventors believe that the presenceof an Fc receptor binding region in the antibodies and fragments of thisinvention causes inhibition of NK cell lysis in the presence of a cellbearing an Fc receptor. Those antibodies and fragments that lack an Fcreceptor binding region are capable of reconstituting NK cell lysis oftarget cells bearing HLA-E or Qa1^(b) on their cell surface. Such targetcells are typically protected against NK cell lysis through theinteraction of HLA-E or Qa1^(b) with the NKG2A receptor.

The invention also provides compositions comprising the antibodies andfragments of this invention, as well as therapeutic methods utilizingsuch compositions for treating different diseases and disorders. Theinvention further provides methods for using non-human primates toevaluate and characterize the activity, toxicity and proper dosingregimen of an antibody or fragment thereof against human NKG2A.

In one aspect, accordingly, the present invention provides an activatingantibody that is a monoclonal antibody or a fragment thereofcharacterized by: a) specifically binding to NKG2A; b) not specificallybinding to an Fc receptor; and c) when bound to NKG2A on a human NKcell, causing said NK cell to lyse a target human cell bearing HLA-E orQa1^(b) on the target cell surface, when said target cell comes intocontact with said NK cell. Preferably, the monoclonal antibody orfragment does not bind to other human NKG2 receptors, specifically theactivating receptors NKG2C or NKG2E. Even more preferred is that theantibody or fragment of this invention completely compete with ananti-NKG2 monoclonal selected from Z199 or Z270.

In one preferred embodiment, the monoclonal antibody or a fragmentthereof is capable of binding to a non-human primate NKG2A. Even morepreferred is when upon binding to NKG2A on a non-human primate NK cell,the monoclonal antibody or a fragment thereof has the ability toreconstitute lysis of a target non-human primate cell bearing HLA-E onthe target cell surface, when said target cell comes into contact withsaid NK cell.

In another preferred embodiment, the monoclonal antibody or a fragmentthereof comprises the amino acids sequence of the variable heavy chainregion of Z270 or the variable light chain region of Z270. In analternate preferred embodiment, the monoclonal antibody or a fragmentthereof comprises the amino acids sequence of the variable heavy chainregion of Z199 or the variable light chain region of Z199.

In yet another preferred embodiment, the monoclonal antibody or afragment thereof comprises a mouse or human IgG₁ constant region thathas been modified to prevent binding to an Fc receptor, or a human IgG₄constant region.

In another preferred embodiment, the antibody or fragment is chimeric orhumanized. More preferred is an antibody or fragment thereof thatcomprises ch270VK or ch270VH.

In another embodiment, the antibody or fragment thereof is derivatizedto enhance its bioavailability or stability in vivo. In anotherembodiment, the antibody is derivatized with PEG.

The activating antibodies and fragments of this invention are useful toreconstitute lysis of certain target cells that are normally resistantto NK cell-mediated lysis. Thus, in another embodiment the inventionprovides a method of reconstituting NK cell-mediated lysis of a targetcell in a population comprising a NK cell and said target cell, whereinsaid NK cell is characterized by NKG2A on its surface, and said targetcell is characterized by the presence of HLA-E or Qa1^(b) on itssurface, said method comprising the step of contacting said NK cell witha monoclonal antibody or a fragment described above. Preferably, thetarget cell is a human cell. More preferably, the target cell is adendritic cell (“DC”), a cancer cell or a virally-infected cell. Mostpreferably, the target is a mature dendritic cell (“mDC”).

The activating antibodies and fragments thereof may be formulated intocompositions additionally comprising a pharmaceutically acceptablecarrier or excipient. Such composition may be formulated so as to besuitable for pharmaceutical administration. The pharmaceuticalcompositions may optionally comprise a second therapeutic agent usefulfor the particular disease or condition being treated. All suchcompositions are also part of the present invention.

The activating antibody compositions of this invention may be utilizedto treat or prevent in a patient an autoimmune or inflammatory disorder,or an immune response; or to treat in a patient a cancer characterizedby the presence of a cancer cell expressing HLA-E or Qa1^(b) on itssurface, or a viral disease characterized by the presence of a virallyinfected cell expressing HLA-E or Qa1^(b) on its surface. These methodsmay additionally comprise the step of administering to the patient asecond therapeutic agent useful for the particular disease or conditionbeing treated. The second therapeutic agent may be administered eitheras a separate dosage form or as part of said composition.

In one embodiment, the second therapeutic agent in the compositionscomprising and the methods utilizing an activating antibody or fragmentof the invention is a compound that agonizes an activating an NK cellreceptor, such as NKp30, NKp44, and NKp46. In another embodiment, thesecond therapeutic agent is an antagonist of an inhibitory NK cellreceptor, such as an inhibitor KIR receptor. In another embodiment, thesecond therapeutic agent is an antagonist of TGF-beta 1. In anotherembodiment, the second therapeutic agent is selected from the groupconsisting of a cytokine inhibitor, a hematopoietic growth factor, apain reliever, insulin, an anti-inflammatory agent, and animmunosuppressant. In another embodiment, the second therapeutic agentis an anticancer compound or an antiemetic. In another embodiment, thesecond therapeutic agent is an antiviral compound.

In another embodiment, the autoimmune or inflammatory disorder to beprevented or treated is selected from the group consisting of autoimmunehemolytic anemia, pernicious anemia, polyarteritis nodosa, systemiclupus erythematosus, Wegener's granulomatosis, Alzheimer's disease,autoimmune hepatitis, Behcet's disease, Crohn's disease, primary bilarycirrhosis, scleroderma, ulcerative colitis, Sjögren's syndrome, Type 1diabetes mellitus, uveitis, Graves' disease, thyroiditis, Type 1diabetes mellitus, myocarditis, rheumatic fever, ankylosing spondylitis,rheumatoid arthritis, glomerulonephritis, sarcoidosis, dermatomyositis,myasthenia gravis, polymyositis, Guillain-Barré syndrome, multiplesclerosis, alopecia areata, pemphigus/pemphigoid, psoriasis, andvitiligo.

In another aspect, the present invention provides an inhibitorymonoclonal antibody or an inhibitory fragment thereof characterized by:a) specifically binding to NKG2A; b) specifically binding to an Fcreceptor; c) not binding to NKG2C or NKG2E; d) complete competition withZ270 or Z199; e) being able to inhibit NK cell lysis of an NKcell-susceptible target cell, wherein said cross-linking monoclonalantibody is not Z199. In one preferred embodiment, the inhibitoryantibody is further characterized by binding to a non-human primateNKG2A.

In a more preferred embodiment, the inhibitory antibody or fragmentthereof comprises an amino acid sequence of the variable light chainregion of Z270 or an amino acid sequence of the variable heavy chainregion of Z270. In one of the most preferred embodiments, the antibodyis Z270.

In another preferred embodiment, the inhibitory antibody or fragment ischimeric or humanized. More preferred is an inhibitory antibody orinhibitory fragment thereof that comprises ch270VK or ch270VH. Inanother of the most preferred embodiments, the antibody is chZ270 orZ270.

In another embodiment, the invention provides a composition comprisingan effective amount of an inhibitory antibody or inhibitory fragmentthereof described above, or Z199; and a pharmaceutically acceptablecarrier or excipient. These inhibitory antibody compositions arepreferably formulated for pharmaceutical use.

The inhibitory antibody compositions of this invention optionallycomprise a second therapeutic agent useful to treat a disease orcondition characterized by undesired NK cell-mediated lysis of othercells, hyperactive NK cell activity, or unwanted NK cell proliferation.Such second therapeutic agents may be selected from, for example, acytokine, an anticancer compound (such as a chemotherapeutic compound,an anti-angiogenic compound, an apoptosis-promoting compound, a hormonalagent, a compound that interferes with DNA replication, mitosis and/orchromosomal segregation, or an agent that disrupts the synthesis andfidelity of polynucleotide precursors), an adjunct compound, a compoundcapable of stimulating an inhibitory NK cell receptor (such as naturalligands, antibodies or small molecules that can stimulate the activityof CD94/NKG2A receptors, or an inhibitory KIR receptor such as KIR2DL1,KIR2DL2, KIR2DL3, KIR3DL1, and KIR3DL2), or an inhibitor of anactivating NK cell receptor (such as NKp30, NKp44, or NKp46).

The inhibitory antibody and fragments of this invention may be utilizedin a method of reducing NK cell-mediated lysis of cells. Alternatively,the inhibitory antibody and fragments of this invention may be utilizedin a method of reducing the number of NK cells in a cell population.Both of these methods comprise the step of contacting said NK cell withthe inhibitor monoclonal antibody or fragment.

The pharmaceutically suitable compositions of this invention comprisingan inhibitory antibody may be employed in a method of treating orpreventing a patient suffering from a condition or disordercharacterized by undesired NK cell-mediated lysis of other cells,hyperactive NK cell activity, or unwanted NK cell proliferation, saidmethod comprising the step of administering to the patient saidcomposition. One such condition is NK-LDGL. NK-LDGL (NK-typelymphoproliferative disease of granular lymphocytes; alternativelycalled NK-LGL) refers to a class of proliferative disorders that iscaused by the clonal expansion of NK cells or NK-like cells, i.e., largegranular lymphocytes showing a characteristic combination of surfaceantigen expression (e.g., CD3-, CD56+, CD16+, etc.; see, e.g., Loughran(1993) Blood 82:1).

In an alternate embodiment, any of the methods utilizing an inhibitoryantibody of this invention may comprise the additional step ofadministering to said patient a second therapeutic agent. The secondtherapeutic agent is an agent normally used to treat a disease orcondition characterized by undesired NK cell-mediated lysis of othercells, hyperactive NK cell activity, or unwanted NK cell proliferation.Examples of such agents are set forth above. The second therapeuticagent may be administered as a separate dosage form or as a component ofthe inhibitory antibody or fragment composition.

In another aspect, the present invention provides kits comprising anyone or more of the herein-described antibodies or fragments thereof.Typically, the kit also comprises instructions for using the antibodiesaccording to the present methods. In a related embodiment, the kitadditionally comprises, in a separate vessel, a second therapeuticagent, such as any of those described above for use in conjunction witheither activating or inhibitory antibodies or fragments in the treatmentor prevention of various diseases or conditions.

According to another aspect, the invention provides a method ofevaluating an antibody against human NKG2A comprising the steps of: a)contacting said antibody with a non-human primate cell characterized byNKG2A on its surface, or a non-human primate NKG2A polypeptide; and b)assessing the ability of said antibody to bind to or affect the activityof said cell or polypeptide. In a related embodiment, the method is usedto evaluate an activating antibody; said antibody is contacted with acell population comprising a non-human primate NK cell and a targetcell, wherein said NK cell is characterized by NKG2A on its surface, andsaid target cell is characterized by the presence of HLA-E on itssurface; and said assessing step is determining if said target cell islysed.

In another embodiment, the invention provides a method of producing anantibody suitable for use in disease treatment in humans, said methodcomprising: a) immunizing a nonhuman mammal with a compositioncomprising human NKG2A; b) selecting a monoclonal antibody that bindsNKG2A, but not NKG2C or NKG2E; c) rendering said antibody suitable foruse in humans; d) administering said antibody to a nonhuman primate; ande) evaluating the ability of said antibody to bind to NKG2A in vivo insaid primate and the tolerance of said primate to said antibody. If theantibody binds to and is tolerated by said nonhuman primate, itindicates that said antibody is suitable for use in disease treatment inhumans. In a preferred embodiment, the method comprises the additionalstep of modifying said antibody to not bind an Fc receptor prior to stepd.

The invention also provides an antibody produced by this method.

In yet another embodiment, the invention provides a method ofidentifying a suitable administration regimen for a therapeutic antibodydirected against human NKG2A, said method comprising: a) administeringsaid antibody to a nonhuman primate using a series of administrationregimens in which the dose or frequency of said antibody is varied; andb) determining the activity of NKG2A-expressing cells in said non-humanprimate and the tolerance of said primate for each of saidadministration regimens. Once it is determined that a regimen istolerated by said primate and leads to a detectable modulation in saidactivity of NKG2A-expressing cells, that administration regimen isconsidered suitable for use in humans.

According to an alternative embodiment, the invention provides aconjugate comprising: a) an inhibitory or activating antibody, and b) acytotoxic agent. The resulting conjugate is used to kill NK cells. Thus,conjugation of an activating antibody with a cytotoxic agent willproduce a molecule that will kill the NK cell, as opposed to theactivation of that cell achieved by the activating antibody alone. Thecytotoxin/antibody conjugates of this invention can be formulated intocompositions and used in methods in a manner similar to the inhibitoryantibodies of this invention.

DESCRIPTION OF THE FIGURES

FIG. 1 depicts the effect of three different concentrations of Z270 onNK cell lysis of HLA-E expressing PHA blasts at varying ratios of NKcells to PHA blasts.

FIG. 2 depicts the effect of three different concentrations of Z199 onNK cell lysis of HLA-E expressing PHA blasts at varying ratios of NKcells to PHA blasts.

FIG. 3 depicts the effect of an F(ab′)2 fragment of Z270 on NK celllysis of HLA-E expressing PHA blasts.

FIG. 4 shows binding to cynomolgus monkey NK cells of antibody Z270 aswell as IgG1 and anti-CD16, demonstrating that Z270 binds to cynomolgusmonkey NK cells. Binding was also shown for macaca mulatta and baboons.

DETAILED DESCRIPTION OF THE INVENTION Introduction

The present invention provides novel antibodies against NKG2A thatactivate NK cell-mediated lysis of target cells characterized by thepresence of cells expressing HLA-E or Qa1^(b) on their cell surface,methods for producing, evaluating and characterizing those antibodiesfor therapeutic use, and compositions comprising and methods of usingthose antibodies for the treatment of autoimmune or inflammatorydisorders and other conditions characterized by the presence of cellsexpressing HLA-E or Qa1^(b) on their cell surface, such as dendriticcells. The present invention is based, in part, on the surprisingdiscovery that NKG2A has a primary responsibility for inhibiting thelysis of mature dendritic cells by many NK cells. Mature dendritic cellsexpress significant levels of HLA-E, which acts through NKG2A receptorspresent on NK cells to inhibit the targeting of the dendritic cells.Accordingly, without being bound by the following theory, it is believedthat blocking the NKG2A-mediated inhibition of NK cells leads to anincrease in dendritic cell targeting by NK cells, thereby providing aneffective treatment for autoimmune or inflammatory disorders or indeedany condition that could be alleviated or cured by reducing the activityof dendritic cells, particularly mature dendritic cells. The presentinvention thus also provides methods of, more generally, inhibiting orreducing the number of dendritic cells, preferably mature dendriticcells, in a mammal, as well as to generally reduce an immune response,preferably an autoreactive immune response.

Conversely, the present invention also provides novel antibodies againstNKG2A that inhibit NK cell-mediated lysis of target cells, methods ofproducing, evaluating and characterizing those antibodies fortherapeutic use, and compositions comprising and methods of using thoseantibodies for the treatment of autoimmune disorders or transplantrejection.

Definitions

As used herein, the following terms have the meanings ascribed to themunless specified otherwise.

As used herein, “NK” cells refers to a sub-population of lymphocytesthat is involved in non-conventional immunity. NK cells can beidentified by virtue of certain characteristics and biologicalproperties, such as the expression of specific surface antigensincluding CD16, CD56 and/or CD57, the absence of the alpha/beta orgamma/delta TCR complex on the cell surface, the ability to bind to andkill cells that fail to express “self” MHC/HLA antigens by theactivation of specific cytolytic enzymes, the ability to kill tumorcells or other diseased cells that express a ligand for NK activatingreceptors, and the ability to release protein molecules called cytokinesthat stimulate or inhibit the immune response. Any of thesecharacteristics and activities can be used to identify NK cells, usingmethods well known in the art.

Dendritic cells are a heterogeneous population of immune cells producedin the bone marrow (see, e.g., O'Neill et al. (2004) Blood104:2235-2246, Mohamadzadeh et al. (2004) J Immune Based Ther Vaccines.2004; 2: 1; the entire disclosures of which are herein incorporated byreference). As referred to herein, DCs can include DC precursors,immature DCs, and mature DCs. DC precursors and immature DCs are lineagenegative (CD3−CD14−CD19−CD56−) HLA-DR+ mononuclear cells. These cellscan be further classified into two populations, myeloid DCs andplasmacytoid DCs. Myeloid DCs are CD11c+ and CD123 low and have amonocytoid appearance, and plasmacytoid DCs are CD11c- and CD123 high,with morphological features similar to plasma cells. Following antigencapture, DCs undergo a process of maturation in which the capturedantigens are processed into peptides and loaded onto MHC class I or IIfor presentation on the cell surface. Mature DCs show lower phagocyticuptake, have cytoplasmic extensions called veils, migrate to lymphoidtissues, and express characteristic markers such as CD83 and DC-LAMP.TLRs are also expressed in DCs, with different DC types expressingdifferent TLR markers (see, e.g., O'Neill et al. (2004).

NKG2A (OMIM 161555, the entire disclosure of which is hereinincorporated by reference) is a member of the NKG2 group of transcripts(Houchins, et al. (1991) J. Exp. Med. 173:1017-1020). NKG2A is encodedby 7 exons spanning 25 kb, showing some differential splicing. NKG2A isan inhibitory receptor found on the surface of NK cells. Like inhibitoryKIR receptors, it possesses an ITIM in its cytoplasmic domain. As usedherein, “NKG2A” refers to any variant, derivative, or isoform of theNKG2A gene or encoded protein. Also encompassed are any nucleic acid orprotein sequences sharing one or more biological properties or functionswith wild type, full length NKG2A, and sharing at least 70%, 80%, 90%,95%, 96%, 97%, 98%, 99%, or higher nucleotide or amino acid identity.NKG2A is also referred to as the “NKG2A receptor” throughout thisdisclosure.

NKG2C (OMIM 602891, the entire disclosure of which is hereinincorporated by reference) and NKG2E (OMIM 602892, the entire disclosureof which is herein incorporated by reference) are two other members ofthe NKG2 group of transcripts (Gilenke, et al. (1998) Immunogenetics48:163-173). NKG2C and NKG2E are activating receptors found on thesurface of NK cells. As used herein, “NKG2C” and “NKG2E” refer to anyvariant, derivative, or isoform of the NKG2C or NKG2E gene or encodedprotein, respectively. Also encompassed are any nucleic acid or proteinsequences sharing one or more biological properties or functions withwild type, full length NKG2C or NKG2E, and sharing at least 70%, 80%,90%, 95%, 96%, 97%, 98%, 99%, or higher nucleotide or amino acididentity with the disclosed gene or encoded protein.

CD94 (OMIM 602894, the entire disclosure of which is herein incorporatedby reference in its entirety) is an antigen preferentially expressed onNK cells (Chang et al. (1995) Europ. J. Immun. 25: 2433-2437). CD94 isexpressed as 3 major transcripts of 0.8, 1.8, and 3.5 kb and a minortranscript of 5.5 kb in NK cell lines, and encodes a protein with a147-amino acid extracellular domain and several motifs characteristic ofC-type lectins. The amino acid sequence of CD94 is 27 to 32% identicalto those of NKG2 family members NKG2A, NKG2C, NKG2D, and NKG2E. Due tothe virtual absence of a cytoplasmic domain, CD94 requires associationwith other receptors forming disulfide-bonded heterodimers with NKG2A,NKG2C, and NKG2E (Lazetic et al. (1996) J. Immun. 157: 4741-4745). Asused herein, “CD94” refers to any variant, derivative, or isoform of theCD94 gene or encoded protein. Also encompassed are any nucleic acid orprotein sequences sharing one or more biological properties or functionswith wild type, full length CD94, and sharing at least 70%, 80%, 90%,95%, 96%, 97%, 98%, 99%, or higher nucleotide or amino acid identity.

HLA-E (OMIM 143010, the entire disclosure of which is hereinincorporated by reference) is a nonclassical MHC molecule that isexpressed on the cell surface and regulated by the binding of peptidesderived from the signal sequence of other MHC class I molecules. HLA-Ebinds natural killer (NK) cells and some T cells, binding specificallyto CD94/NKG2A, CD94/NKG2B, and CD94/NKG2C, and not to the inhibitory KIRreceptors (see, e.g. OMIM 604936, the entire disclosure of which isherein incorporated by reference) (see, e.g., Braud et al. (1998) Nature391:795-799, the entire disclosure of which is herein incorporated byreference). Surface expression of HLA-E is sufficient to protect targetcells from lysis by CD94/NKG2A+NK cell clones. As used herein, “HLA-E”refers to any variant, derivative, or isoform of the HLA-E gene orencoded protein. Also encompassed are any nucleic acid or proteinsequences sharing one or more biological properties or functions withwild type, full length HLA-E, and sharing at least 70%, 80%, 90%, 95%,96%, 97%, 98%, 99%, or higher nucleotide or amino acid identity.

Qa1^(b) is a mouse cell surface antigen that is the physiological ligandfor NKG2A. As used herein, “Qa1^(b)” refers to any variant, derivative,or isoform of the Qa1^(b) gene or encoded protein. Also encompassed areany nucleic acid or protein sequences sharing one or more biologicalproperties or functions with wild type, full length Qa1^(b), and sharingat least 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, or higher nucleotide oramino acid identity.

“Autoimmune” disorders include any disorder, condition, or disease inwhich the immune system mounts a reaction against self cells or tissues,due to a breakdown in the ability to distinguish self from non-self orotherwise. Examples of autoimmune disorders include Hashimoto'sthyroiditis, pernicious anemia, Addison's disease, type I diabetes,rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis,Sjogren's syndrome, lupus erythematosus, multiple sclerosis, myastheniagravis, Reiter's syndrome, Grave's disease, polymyositis, GuillainBarré, Wegener's granulomatosis, polyarteritis nodosa, polymyalgiarheumatica, temporal arteritis, Bechet's disease, Churg-Strausssyndrome, Takayasu's arteritis, and others. An “inflammatory disorder”includes any disorder characterized by an unwanted immune response.Autoimmune and inflammatory disorders can involve any component of theimmune system, and can target any cell or tissue type in the body.

The terms “inhibiting,” “reducing,” “blocking,” “downmodulating,” and“downregulating,” with respect to NKG2A activity refer to any process,method, or compound that can slow down, reduce, reverse, or in any waynegatively affect the stimulation or expression of NKG2A receptors oncells, preferably NK cells. These terms can refer to compounds thatinhibit the stimulation of NKG2A by a ligand, that act antagonisticallyin the absence of a ligand to decrease the activity of the receptor,that decrease the expression level of the receptor, that blockNKG2A-triggered signaling or gene expression, or that block any otheractivity of the cell that results from NKG2A activation. In a preferredembodiment, the inhibiting compound or method prevents the binding ofthe receptor by a ligand, e.g. HLA-E. The number of NKG2A receptormolecules or any of the herein-described activities can be measured inany standard way, e.g. as disclosed elsewhere in the presentapplication.

The term “antibody,” as used herein, refers to polyclonal and monoclonalantibodies. Depending on the type of constant domain in the heavychains, antibodies are assigned to one of five major classes: IgA, IgD,IgE, IgG, and IgM. Several of these are further divided into subclassesor isotypes, such as IgG1, IgG2, IgG3, IgG4, and the like. An exemplaryimmunoglobulin (antibody) structural unit comprises a tetramer. Eachtetramer is composed of two identical pairs of polypeptide chains, eachpair having one “light” (about 25 kDa) and one “heavy” chain (about50-70 kDa). The N-terminus of each chain defines a variable region ofabout 100 to 110 or more amino acids that is primarily responsible forantigen recognition. The terms “variable light chain (V_(L))” and“variable heavy chain (V_(H))” refer to these light and heavy chainsrespectively. The heavy-chain constant domains that correspond to thedifferent classes of immunoglobulins are termed “alpha,” “delta,”“epsilon,” “gamma” and “mu,” respectively. The subunit structures andthree-dimensional configurations of different classes of immunoglobulinsare well known. IgG and/or IgM are the preferred classes of antibodiesemployed in this invention, with IgG being particularly preferred,because they are the most common antibodies in the physiologicalsituation and because they are most easily made in a laboratory setting.

Preferably the antibody of this invention is a monoclonal antibody.Particularly preferred are humanized, chimeric, human, orotherwise-human-suitable antibodies. The term “antibody” also includesany fragment or derivative of any of the herein described antibodiesexcept in those contexts of the present disclosure where such inclusioncauses a redundancy (e.g., a specific reference to “an antibody or afragment thereof”). In one preferred embodiment, the antibodies arenon-depleting antibodies, meaning that they bind to NK cells and inhibitNKG2A stimulation (which leads to the lysis of cells bearing HLA-E orQa1^(b) on their cell surface), but do not lead to the killing of theNKG2A expressing cell. Non-depleting antibodies or antibody fragmentsare those that are not recognized, or only poorly recognized, by Fcreceptors, such as IgG4 antibodies, antibody fragments lacking the Fcportion, or any other antibody whose Fc tail has been modified to reduceor eliminate binding by Fc receptors (see, e.g., WO03101485, the entiredisclosure of which is herein incorporated by reference).

In another preferred embodiment, the antibodies or antibody fragmentsbind to an Fc receptor. Such antibodies and fragments causecross-linking of NKG2A molecules leading to inhibition of NK cellactivity and, in some cases, to NK cell death.

The term “specifically binds to” means that an antibody can bind,preferably in a competitive binding assay, to the binding partner, e.g.NKG2A, as assessed using either recombinant forms of the protein,epitopes therein, or native proteins present on the surface of isolatedNK or other cells. Competitive binding assays and other methods fordetermining specific binding are further described below and are wellknown in the art.

A “human-suitable” antibody refers to any antibody, derivatizedantibody, or antibody fragment that can be safely used in humans for,e.g. the therapeutic methods described herein. Human-suitable antibodiesinclude all types of humanized, chimeric, or fully human antibodies, orany antibodies in which at least a portion of the antibodies is derivedfrom humans or otherwise modified so as to avoid the immune responsethat is generally provoked when native non-human antibodies are used.

For the purposes of the present invention, a “humanized” antibody refersto an antibody in which the constant and variable framework region ofone or more human immunoglobulins is fused with the binding region, e.g.the CDR, of an animal immunoglobulin. Such humanized antibodies aredesigned to maintain the binding specificity of the non-human antibodyfrom which the binding regions are derived, but to avoid an immunereaction against the non-human antibody.

A “chimeric antibody” is an antibody molecule in which (a) the constantregion, or a portion thereof, is altered, replaced or exchanged so thatthe antigen binding site (variable region) is linked to a constantregion of a different or altered class, effector function and/orspecies, or an entirely different molecule which confers new propertiesto the chimeric antibody, e.g., an enzyme, toxin, hormone, growthfactor, drug, etc.; or (b) the variable region, or a portion thereof, isaltered, replaced or exchanged with a variable region having a differentor altered antigen specificity.

A “human” antibody is an antibody obtained from transgenic mice or otheranimals that have been “engineered” to produce specific human antibodiesin response to antigenic challenge (see, e.g., Green et al. (1994)Nature Genet 7:13; Lonberg et al. (1994) Nature 368:856; Taylor et al.(1994) Int Immun 6:579, the entire teachings of which are hereinincorporated by reference). A fully human antibody also can beconstructed by genetic or chromosomal transfection methods, as well asphage display technology, all of which are known in the art (see, e.g.,McCafferty et al. (1990) Nature 348:552-553). Human antibodies may alsobe generated by in vitro activated B cells (see, e.g., U.S. Pat. Nos.5,567,610 and 5,229,275, which are incorporated in their entirety byreference).

Within the context of this invention, “active” or “activated” NK cellsdesignate biologically active NK cells, more particularly NK cellshaving the capacity of lysing target cells. For instance, an “active” NKcell is able to kill cells that express an NK activating receptor-ligandand fails to express “self” MHC/HLA antigens (KIR-incompatible cells).Such cells are also referred to herein as “NK cell-susceptible targetcells.” Examples of such target cells, which are suitable for use inredirected killing assays, are P815 and K562 cells. However, any of anumber of cell types can be used and are well known in the art (see,e.g., Sivori et al. (1997) J. Exp. Med. 186: 1129-1136; Vitale et al.(1998) J. Exp. Med. 187: 2065-2072; Pessino et al. (1998) J. Exp. Med.188: 953-960; Neri et al. (2001) Clin. Diag. Lab. Immun. 8:1131-1135).“Active” or “activated” cells can also be identified by any otherproperty or activity known in the art as associated with NK activity,such as cytokine (e.g. IFN-γ and TNF-α) production of increases in freeintracellular calcium levels. For the purposes of the present invention,activated NK cells ideally refer to NK cells in which NKG2A receptorsare not stimulated, and in which an NCR, preferably NKp30, isstimulated, thereby leading to cytotoxicity of the cell against maturedendritic cells.

The term “NKG2A stimulation,” as used herein refers to the process thatoccurs in a cell bearing NKG2A, e.g., a NK cell, when NKG2A binds to itsnatural ligand (e.g., HLA-E or Qa1^(b)) or a functional fragmentthereof. Because NKG2A is an inhibitory receptor, such binding can causeinhibition of NK cell activity. Thus, “inhibition of NKG2A stimulation”refers to a process whereby the binding of NKG2A to its natural ligandor a functional fragment thereof is either reduced or prevented, wherethe binding occurs, but does not cause inhibition of NK cell activity.

Thus, the term “activating antibody,” as used herein in reference toantibodies against NKG2A, is intended to mean an antibody which, throughbinding to NKG2A on a NK cell, prevents association of NKG2A with itsnatural ligand (e.g., HLA-E or Qa1^(b)) on a target cell, or preventsNKG2A dependent signal transduction normally mediated by a HLA-Epositive target, and thus reverses the inhibition of lysis of the targetcell by the NK cell caused by the association of NKG2A with the ligand.Thus, an activating antibody causes inhibition of NKG2A stimulation.

The term “inhibitory antibody,” as used herein in reference toantibodies against NKG2A, is intended to mean an antibody which, throughbinding to NKG2A on a NK cell, causes inhibition of a NK cell's abilityto lyse cells that would otherwise be lysed. The inhibitory antibodiesof this invention typically cause cross-linking of NKG2A molecules in aNK cell, which leads to inhibition, and sometimes death, of that NKcell. It should be noted that an inhibitory antibody against NKG2A ofthis invention may prevent the association of NKG2A with its naturalligand or an active fragment thereof, but will not result in the lysisof a cell bearing that natural ligand because the NK cell's ability tolyse cells had been inhibited by the antibody.

The terms “isolated” “purified” or “biologically pure” refer to materialthat is substantially or essentially free from components which normallyaccompany it as found in its native state. Purity and homogeneity aretypically determined using analytical chemistry techniques such aspolyacrylamide gel electrophoresis or high performance liquidchromatography. A protein that is the predominant species present in apreparation is substantially purified.

The term “biological sample” as used herein includes but is not limitedto a biological fluid (for example serum, lymph, blood), cell sample ortissue sample (for example bone marrow).

The terms “polypeptide,” “peptide” and “protein” are usedinterchangeably herein to refer to a polymer of amino acid residues. Theterms apply to amino acid polymers in which one or more amino acidresidue is an artificial chemical mimetic of a corresponding naturallyoccurring amino acid, as well as to naturally occurring amino acidpolymers and non-naturally occurring amino acid polymer.

The term “recombinant” when used with reference, e.g., to a cell, ornucleic acid, protein, or vector, indicates that the cell, nucleic acid,protein or vector has been modified by the introduction of aheterologous nucleic acid or protein or the alteration of a nativenucleic acid or protein, or that the cell is derived from a cell somodified. Thus, for example, recombinant cells express genes that arenot found within the native (nonrecombinant) form of the cell or expressnative genes that are otherwise abnormally expressed, under expressed ornot expressed at all.

The term “competes with” when referring to a particular monoclonalantibody (e.g. Z199 or Z270) means that the antibody or fragment thereofbeing tested reduces the binding of that reference monoclonal antibody(e.g. Z199 or Z270) to NKG2A (as compared to a control comprising thatreference monoclonal antibody and NKG2A, but lacking the test antibody)in a binding assay using either recombinant NKG2A molecules or surfaceexpressed NKG2A molecules. For example, if an antibody reduces bindingof Z270 to a human NKG2A molecule in a binding assay, the antibody“competes” with Z270 for binding to human NKG2A.

The term “completely competes with,” as used herein means that the testantibody binds to substantially or essentially the same epitope as thereference monoclonal.

As used herein, an “effective amount” refers to any amount that isnecessary or sufficient for achieving or promoting a desired outcome. Insome instances an effective amount is a therapeutically effectiveamount. A therapeutically effective amount is any amount that isnecessary or sufficient for promoting or achieving a desired biologicalresponse in a subject. The effective amount for any particularapplication can vary depending on such factors as the disease orcondition being treated, the particular agent being administered, thesize of the subject, or the severity of the disease or condition. One ofordinary skill in the art can empirically determine the effective amountof a particular agent without necessitating undue experimentation.

The term non-human primates include any mammals within the OrderPrimates, including apes, New World monkeys, Old World monkeys,prosimians, Pongo pygmaeus pygmaeus (Borneo orangutan), Pongo pygmaeusabelii (Sumatran orangutan), Gorilla gorilla (western lowland gorilla),Pan paniscus (bonobo), Pan troglodytes (chimpanzee), Pan troglodytesverus (chimpanzee), Lemur fulvus (brown lemur), Saguinus fuscicollis(white-lipped tamarin), Saguinus labiatus (red-bellied tamarin),Callicebus molloch pallescens (Paraguayan titi), Saimiri sciureus(squirrel monkey), Ateles geoffroyi (black-handed spider monkey),Lagothrix lagotricha (woolly monkey), Macaca arctoides (stumptailmacaque), Macaca fascicularis (crab-eating macaque), Macaca fuscata(Japanese macaque), Macaca mulatta (rhesus monkey), Macaca nemestrina(pigtailed macaque), Macaca nigra (Celebes ape), Erythrocebus patas(patas monkey), baboons, marmosets, capuchins, cynomolgus, howlers,spider monkeys, mandrills, guenon, patas monkeys, colobus, gibbons,lemurs, aye-ayes, loris, bushbabies, and tarsiers. In a preferredembodiment, the nonhuman primate used in the present invention is not anape, e.g. is a nonhuman primate other than a chimpanzee, gorilla,orangutan, or gibbon. For the purposes of the invention, assays said tobe carried out using nonhuman primates can include in vivo assays inwhich antibodies are administered to the primates, ex vivo assays inwhich, e.g. cells taken from a primate are treated with the antibodiesand returned to the primate, and in vitro assays involving cells,proteins, or tissue taken from a primate.

If a mammal such as a nonhuman primate is said to “tolerate” anadministration regime of an anti-NKG2A antibody, it means that theadministration is not lethal and does not have any severe side effectsin the animal, although side effects may be still be present as long asthey are not severe, and, generally, that they are outweighed by thetherapeutic benefit provided by the administration.

Obtaining Compounds that Specifically Bind to NKG2A

The present invention involves both activating and inhibitory antibodiesthat bind to NKG2A on immune cells, preferably NK cells, as well astheir identification, production, evaluation and use. One way ofidentifying such antibodies is to find those that are capable of bindingto NKG2A. Once specifically binding antibodies are identified, they canbe tested for their ability to inhibit or activate NKG2A, e.g. on NKcells. It will be appreciated, however, that carrying out such bindingassays is in no way necessary for the practice of the present invention.

Any of a wide variety of assays can be used to assess binding of anantibody to NKG2A. Protocols based upon ELISAs, radioimmunoassays,Western blotting, BIACORE, and other competition assays, inter alia, aresuitable for use and are well known in the art.

For example, simple binding assays can be used, in which a test antibodyis incubated in the presence of a target protein or epitope (e.g., NKG2Aor a portion thereof), unbound antibodies are washed off, and thepresence of bound antibodies is assessed using, e.g., radiolabels,physical methods such as mass spectrometry, or direct or indirectfluorescent labels detected using, e.g., cytofluorometric analysis (e.g.FACScan). Such methods are well known to those of skill in the art. Anyamount of binding above the amount seen with a control, non-specificantibody indicates that the antibody binds specifically to the target.

In such assays, the ability of the test antibody to bind to the targetcell or human NKG2A can be compared with the ability of a (negative)control protein, e.g. an antibody raised against a structurallyunrelated antigen, or a non-Ig peptide or protein, to bind to the sametarget. Antibodies or fragments that bind to the target cells or NKG2Ausing any suitable assay with 25%, 50%, 100%, 200%, 1000%, or higherincreased affinity relative to the control protein are said to“specifically bind to” or “specifically interact with” the target, andare preferred for use in the therapeutic methods described below.

In one embodiment, the ability of a test antibody to affect the bindingof a (positive) control antibody against NKG2A, e.g. 3S9, 20d5, Z270 orZ199, or derivatives thereof, is assessed. In another, the ability of atest antibody to affect the binding of a natural ligand for NKG2A, e.g.HLA-E, is measured. 3S9 is described in United States patent publication20030095965, the disclosure of which is herein incorporated byreference. 3S9 binds to NKG2C and NKG2E, as well as to NKG2A. 20d5 is acommercially available antibody (BD Biosciences Pharmingen, Catalog No.550518, USA). 20d5 binds to mouse NKG2A, NKG2E and NKG2C. Z199 is acommercially available antibody (Beckman Coulter, Inc., Product No.IM2750, USA). Z270 is described fully herein. Z270 binds specifically tohuman NKG2A, but not to human NKG2C or NKG2E.

In addition, simple competition assays may be employed in which acontrol antibody (e.g. 3S9, Z270 or Z199) and a test antibody areadmixed (or pre-adsorbed) and applied to a sample containing NKG2A. Incertain embodiments, one would pre-mix the control antibodies withvarying amounts of the test antibody (e.g., 1:10 or 1:100) for a periodof time prior to applying to the NKG2A-containing sample. In otherembodiments, the control and varying amounts of test antibody can simplybe admixed during exposure to the antigen/target sample. As long as onecan distinguish bound from free antibodies (e.g., by using separation orwashing techniques to eliminate unbound antibodies) and the controlantibody from test antibody (e.g., by using species- or isotype-specificsecondary antibodies, by specifically labeling the control antibody witha detectable label, or by using physical methods such as massspectrometry to distinguish between different compounds) one will beable to determine if the test antibody reduces the binding of thecontrol antibody to the antigen, indicating that the test antibodyrecognizes substantially the same epitope as the control.

In the above-described competition assays, the binding of the (labeled)control antibody in the presence of a completely irrelevant antibody isthe control high value. The control low value is obtained by incubatingthe labeled (positive) control antibody (e.g. 3S9, Z270 or Z199) withunlabeled antibody of exactly the same type (e.g. 3S9, Z270 or Z199),where competition would occur and reduce binding of the labeledantibody.

In a test assay, a significant reduction in labeled antibody reactivityin the presence of a test antibody is indicative of a test antibody thatrecognizes the same epitope, i.e., one that “cross-reacts” with thelabeled control antibody. Any test antibody or compound that reduces thebinding of the labeled control to the antigen/target by at least 50% ormore preferably 70%, at any ratio of control:test antibody or compoundbetween about 1:10 and about 1:100 is considered to be an antibody orcompound that binds to substantially the same epitope or determinant asthe control. Preferably, such test antibody or compound will reduce thebinding of the control to the antigen/target by at least 90%.Nevertheless, any compound or antibody that reduces the binding of acontrol antibody or compound to any measurable extent can be used in thepresent invention.

The identification of one or more antibodies that bind(s) tosubstantially the same epitope as the monoclonal antibody in questioncan be readily determined using any one of a variety of immunologicalscreening assays in which antibody competition can be assessed. Suchassays are routine in the art (see, e.g., U.S. Pat. No. 5,660,827, whichis herein incorporated by reference). It will be understood thatactually determining the epitope to which the antibody binds is not inany way required to identify an antibody that binds to the same orsubstantially the same epitope as the monoclonal antibody in question.

In one embodiment, competition can be assessed by a flow cytometry test.For example, cells bearing an NKG2A/CD94 receptor are incubated firstwith a control antibody that is known to specifically bind to thereceptor (e.g., 3S9, Z270 or Z199), and then with the test antibody thathas been labeled with, e.g., a fluorochrome or biotin. The test antibodyis said to compete with the control if the binding obtained withpreincubation with saturating amounts of control antibody is 80%,preferably, 50%, 40% or less of the binding (mean of fluorescence)obtained by the antibody without preincubation with the control.Alternatively, a test antibody is said to compete with the control ifthe binding obtained with a labeled control (by a fluorochrome orbiotin) on cells preincubated with saturating amount of antibody to testis 80%, preferably 50%, 40%, or less of the binding obtained withoutpreincubation with the antibody.

In one preferred example, a simple competition assay may be employed inwhich a test antibody is pre-adsorbed and applied at saturatingconcentration to a surface onto which is immobilized the substrate forthe antibody binding, e.g. NKG2A/CD94 receptor, or epitope-containingportion thereof, which is known to be bound by, e.g., 3S9. The surfaceis preferably a BIACORE chip. The control antibody (e.g. 3S9, Z270 orZ199) is then brought into contact with the surface at asubstrate-saturating concentration and the substrate surface binding ofthe control antibody is measured. This binding of the control antibodyis compared with the binding of the control antibody to thesubstrate-containing surface in the absence of a test antibody. In atest assay, a significant reduction in binding of thesubstrate-containing surface by the control antibody in the presence ofa test antibody is indicative of a test antibody that recognizes thesame epitope, i.e., one that “cross-reacts” with the control antibody.Any test antibody that reduces the binding of the control antibody tothe antigen-containing substrate by at least 30% or more preferably 40%is considered to be an antibody that binds to substantially the sameepitope or determinant as the control antibody. Preferably, such testantibody will reduce the binding of the control antibody to thesubstrate by at least 50%. It will be appreciated that the order ofcontrol and test antibodies can be reversed, that is the controlantibody is first bound to the surface and the test antibody is broughtinto contact with the surface thereafter. Preferably, the antibodyhaving higher affinity for the substrate antigens is bound to thesubstrate-containing surface first since it will be expected that thedecrease in binding seen for the second antibody (assuming theantibodies are cross-reacting) will be of greater magnitude. Furtherexamples of such assays are provided in Saunal et al. (1995) J. Immunol.Meth 183: 33-41, the entire disclosure of which is herein incorporatedby reference.

Preferably, monoclonal antibodies according to this invention thatrecognize an NKG2A will react with an epitope that is present on asubstantial percentage of NK cells in patients with an autoimmune orinflammatory disorder, but will not significantly react with othercells, i.e., immune or non-immune cells that do not express NKG2A.Accordingly, once an antibody that specifically recognizes NKG2A oncells such as NK, preferably human NK cells, is identified, it can betested for its ability to bind to NK cells taken from patients withautoimmune or inflammatory disorders. Similarly, it will be appreciatedthat the present methods can be practiced using multiple antibodies,e.g. directed against different epitopes or isoforms of NKG2A in a waythat is designed to maximally inhibit the stimulation of NKG2A. In oneembodiment, NK cells and dendritic cells are taken from a patient priorto the administration of the antibodies or compounds, and the ability oftest antibodies to overcome NKG2A-mediated inhibition of lysis of thedendritic cells is assessed.

In those embodiments of the invention where specific binding or lack ofspecific binding to other antigens (e.g., NKG2A from other species,NKG2C, NKG2E, Fc receptor) must be measured, assays similar to those setforth above may be employed substituting the appropriate antigen forNKG2A and employing control antibodies that are specific for the antigento which binding is being assayed. Such antigens and control antibodiesare well-known in the art and many are commercially available.

Assessing the Ability of Antibodies to Inhibit NKG2A Stimulation

The identification of activating antibodies of this invention that arecapable of inhibiting the stimulation of NKG2A/CD94 by HLA-E or Qa1^(b)will generally involve cell-based assays to assess NKG2A activity in thepresence of test antibody. In some embodiments, candidate antibodieswill be first identified based on their ability to bind to NKG2A, asdescribed supra. In other embodiments, cell-based screening will beperformed to directly identify antibodies capable of inhibiting NKG2Astimulation, regardless of their binding affinity.

In one embodiment, modulators of NKG2A will be identified using methodsor assays described in U.S. patent application no. 20030171280, Braud etal. (1998) Nature 391:795-799; Lee et al. (1998) PNAS 95:5199-5204;Vance et al. (2002) PNAS 99:868-873; Brooks et al. (1999) J Immunol162:305-313; Miller et al. J Immunol (2003) 171:1369-75; Brooks et al.(1997) J Exp Med 185:795-800; Van Beneden et al. (2001) 4302-4311; U.S.patent application no. 20030095965; the entire disclosures of which areherein incorporated by reference.

In one embodiment, the activating antibodies of this invention areassessed for their ability to inhibit the stimulation of the NKG2Areceptor by ligands. Any of a large number of assays, includingmolecular cell-based, and animal-based models can be used. In typicalembodiments, cell-based assays will be used in which cells, e.g. NKcells expressing NKG2A, are exposed to an NKG2A ligand (or cellsexpressing the ligand), preferably HLA-E, and the ability of theantibody to disrupt the stimulation of the receptor is assessed.

Any of a number of cell-based assays can be used to assess NKG2Aactivity, including gene expression-based activities, cytotoxicity-basedassays, and proliferation assays. In certain embodiments, in vitroassays will use cells, e.g. NK cells, taken from patients with anautoimmune or inflammatory disorder, but in general any NKG2A-expressingcell can be used, including NK cell lines such as YTS or NK-92(available from the ATCC). For example, cell lines can be transfectedwith an NKG2A-encoding transgene and used in the present assays, so longas the stimulation of the expressed receptor alters the activity orproperties of the cells in a detectable way, e.g., activates signaltransduction pathways, affects proliferation, or alters the cytotoxicityof the cells. It will be appreciated that, for such assays, any isoformof NKG2A, CD94, or HLA-E (see, e.g. OMIM refs. 161555, 602894, and143010, the entire disclosures of which are herein incorporated byreference) can be used in such assays (or any other assay or methodinvolving NKG2A described herein).

In one preferred embodiment, a cellular assay is used in whichNKG2A-expressing cells, e.g., NK cells, are incubated with an NKG2Aligand such as HLA-E, or a cell expressing an NKG2A ligand, preferably adendritic cell, and the ability of a test compound to block theinhibition of the NK cell is assessed. In such assays, the lysis of thedendritic cells can itself be measured as a reflection of NK cellactivity.

In one embodiment, cell lines will be established using NK cells frompatients with an autoimmune or inflammatory disorder. In numerousembodiments, assays will be used using non-human cells or non-humanNKG2A/CD94, e.g. non-human primate cells expressing NKG2A/CD94, or mousecells expressing either mouse or human NKG2A/CD94, with the inclusion ofthe appropriate ligand (e.g., in the case of mouse, Qa-1).

The binding of NKG2A to the appropriate ligand causes a number ofphysiological changes in the cell bearing NKG2A. These include changesin gene expression, cell growth, cell proliferation, pH, intracellularsecond messengers, e.g., Ca²⁺, IP3, cGMP, or cAMP, cytokine production,or activity such as cytotoxic activity. Such changes are referred toherein as “NKG2A activity”. Any reversal of these changes in thepresence of a NKG2A ligand can be used to assess the utility of a testantibody. Such reversal is referred to herein as “inhibition of NKG2Aactivity.” In one embodiment, NKG2A activity is assessed by detectingthe expression or activity of NKG2A-responsive genes or proteins, e.g.,SHP-1 or SHP-2 or their targets (see, e.g., Le Drean et al. (1998) Eur JImmunol 28:264-276, Augugliaro et al. (2003) Eur J Immunol 33:1235-141;the entire disclosures of which are herein incorporated by reference).

In any of the herein-described assays, a decrease of 5%, 10%, 20%,preferably 30%, 40%, 50%, most preferably 60%, 70%, 80%, 90%, 95%, orgreater reduction in any detectable measure of NKG2A activity in thecells indicates that the test antibody is a suitable candidate for usein the present methods.

In addition to binding, the ability of antibodies or compounds to causeNK cells to inhibit the proliferation or activation of, or, preferably,kill NKG2A ligand-bearing target cells, e.g. dendritic cells, certaincancer cells, or certain virally-infected cells, can be assessed. In oneembodiment, human NK cells expressing the NKG2A receptor are introducedalong with NKG2A ligand-bearing target cells into plates, e.g., 96-wellplates, and exposed to various amounts of test antibody. By adding avital dye, i.e. one taken up by intact cells, such as AlamarBlue(BioSource International, Camarillo, Calif.), and washing to removeexcess dye, the number of viable cells can be measured by virtue of theoptical density (the more cells killed by the antibody, the lower theoptical density). (See, e.g., Connolly et al. (2001) J Pharm Exp Ther298:25-33, the disclosure of which is herein incorporated by referencein its entirety).

Most preferably, the activating antibodies of this invention do notdemonstrate substantial specific binding to Fc receptors. Suchantibodies may comprise constant regions of various heavy chains thatare known not to bind Fc receptors. One such example is an IgG4 constantregion. Alternatively, antibody fragments that do not comprise constantregions, such as Fab or F(ab′)2 fragments, can be used to avoid Fcreceptor binding. FC receptor binding can be assessed according tomethods known in the art, including for example testing binding of anantibody to Fc receptor protein in a BIACORE assay. Also, any otherantibody type can be used in which the Fc portion is modified tominimize or eliminate binding to Fc receptors (see, e.g., WO03101485,the disclosure of which is herein incorporated by reference). Assays,e.g., cell based assays, to assess Fc receptor binding are well known inthe art, and are described, e.g., in WO03101485.

Preferably, the activating monoclonal antibody of this inventioncomprises an Fc region, preferably an Fc region of the IgG4 or G2subtype, or an Fc region of the IgG1 or G3 subtype that has beenmodified to reduce binding to Fc receptors. Most preferably the G4 or G2Fc region is modified to further minimize or completely abolish bindingto Fc receptors (see, e.g., Angal et al. (1993) Molecular Immunology30:105-108, the entire disclosure of which is herein incorporated byreference.)

IgG4 isotypes are not totally devoid of Fc binding activity, showingsome binding to Fc gamma (“Fcg”) receptors (Newman et al. (2001) Clin.Immunol. (98(2):164-174). An unmodified IgG4 monoclonal antibody cancause cell depletion in vivo (Isaacs et al, (1996) Clin. Exp. Immunol.106, 427). The sequence reported to be primarily responsible for thebinding to Fcg receptors has been defined as LLGGPS (Burton et al,(1992) Adv. Immunol. 51:1). This sequence, located at the N terminal end(EU numbering 234-239) of the heavy chain CH2 region, is conserved inhuman IgG1, IgG3, and murine IgG2a isotypes, all of which bind Fcgreceptors strongly. The wild-type sequence for the IgG4 isotype containsa phenylalanine at position 234, giving the motif FLGGPS. The murineIgG2b isotype, also a poor binder of Fcg receptors, contains thesequence LEGGPS. Newman et al. (2001) incorporated the glutamic acidresidue associated with murine IgG2b into the human wildtype IgG4 CH2domain to give the sequence FEGGPS which reduced even further CDC andADCC activities and virtually eliminated binding to FcgRI and FcgRII invitro. In addition to the introduction of glutamic acid, the replacementof serine 228 by a proline resulted in a molecule that was more stablethan the wild-type IgG4. The IgG4 molecule tends to show inefficientformation of interchain disulfide bonds in the hinge region. Theintroduction of a proline was said to provide rigidity to the hinge andpromote more efficient interchain bonding, and that the presence of aserine at position 228 might promote preferential linkage of intrachainrather than inter-chain disulfide bonds by neighboring cysteinemolecules. Any such modification and others can readily be made to theantibodies of the invention.

In many instances, an inhibitory antibody of this invention can beconverted to an activating antibody of this invention by abolishing mostor all of the former's ability to bind an Fc receptor.

Assessing the Ability of Antibodies Against NKG2A to Inhibit NK CellActivity

The identification of inhibitory antibodies of this invention that arecapable of binding NKG2A and inhibiting NK cell activity, particularlyNK cell lysis of cells is assayed using cell-based assays. Typically, aNKG2A-bearing cell, such as an NK cell, will be contacted with aNK-susceptible cell, such as RMA, a TAP-2 derivative of RMA, P815 andK562 in the presence of varying amounts of test antibody. The percentageof NK-susceptible cells killed in the presence of test antibody iscompared with killing in the absence of antibody.

In another assay for an inhibitory antibody of this invention, NK cellsare incubated in the presence of varying amounts of test antibody todetermine that antibody's direct killing affect on NK cells as comparedto NK cell death in the absence of antibody. NK cell killing may also bedetermined in an assay including the presence of NK-susceptible cells.

In any of the herein-described assays, a decrease of 5%, 10%, 20%,preferably 30%, 40%, 50%, most preferably 60%, 70%, 80%, 90%, or 95% ofNK-susceptible cell killing and/or an increase of 5%, 10%, 20%,preferably 30%, 40%, 50%, most preferably 60%, 70%, 80%, 90%, or 95% ofNK cell death indicates that the test antibody is an inhibitory antibodyof this invention.

Cross-Reactivity of NKG2A Between Primate Species

It has been discovered that there is crossreactivity between human andnonhuman primate NKG2A. Thus, assays to assess the effect of ananti-NKG2A antibody on receptor activity can be carried out using anNKG2A polypeptide from any primate. For example, such assays can beperformed using nonhuman primate NK cells in vitro, or the antibodiescan be administered to nonhuman primates and their ability to modulateNKG2A activity, e.g. as reflected in alterations in NK cell activity,can be measured.

Producing Antibodies

The antibodies of this invention may be produced by any of a variety oftechniques known in the art. Typically, they are produced byimmunization of a non-human animal, preferably a mouse, with animmunogen comprising an NKG2A (or, for all embodiments described herein,for CD94, or HLA-E) receptor on the surface of cells such as T cells orNK cells or dendritic cells. The receptor may comprise entire cells orcell membranes, the full length sequence of an NKG2A (or CD94, etc.), ora fragment or derivative of any NKG2A, typically an immunogenicfragment, i.e., a portion of the polypeptide comprising an epitopeexposed on the surface of cells expressing the receptor. Any isoform orsplicing fragment of NKG2A can be used (see, e.g., OMIM 161555; thedisclosure of which is herein incorporated by reference). Such fragmentstypically contain at least 7 consecutive amino acids of the maturepolypeptide sequence, even more preferably at least 10 consecutive aminoacids thereof. They are essentially derived from the extracellulardomain of the receptor. In preferred embodiments, the NKG2A receptorused to generate antibodies is a human receptor. In certain embodiments,NKG2A present in a heterodimer, e.g. in association with CD94, can beused to generate antibodies.

In a most preferred embodiment, the immunogen comprises a wild-typehuman NKG2A receptor polypeptide in a lipid membrane, typically at thesurface of a cell. In a specific embodiment, the immunogen comprisesintact NK cells, particularly intact human NK cells, optionally treatedor lysed. In a preferred embodiment, the immunogen is an NK cell takenfrom a patient with an autoimmune or inflammatory disorder.

In one embodiment, the antibodies are derived from one or morealready-existing monoclonal antibodies that recognize NKG2A, e.g. Z199(Della Chiesa et al, (2003) Eur. J. Immunol. 33:1657-1666), Z270, 3S9(see, e.g., U.S. patent application no. 20030095965), or 20D5 (Vance etal, (1990) J. Exp. Med. 190(12):1801-1812), the entire disclosures ofwhich are herein incorporated by reference). For certain applications,such antibodies can be directly or indirectly labeled (i.e., used with alabeled secondary antibody) for use as diagnostic antibodies todetermine the presence of NKG2A on the presence of cells, preferably NKcells from patients with autoimmune or inflammatory disorders. Inaddition, the antibodies can be made suitable for human administrationas described herein for use in the present therapeutic methods.

The present antibodies can be full length antibodies or antibodyfragments or derivatives. Examples of antibody fragments include Fab,Fab′, Fab′-SH, F(ab′)₂, and Fv fragments; diabodies; single-chain Fv(scFv) molecules; single chain polypeptides containing only one lightchain variable domain, or a fragment thereof that contains the threeCDRs of the light chain variable domain, without an associated heavychain moiety; single chain polypeptides containing only one heavy chainvariable region, or a fragment thereof containing the three CDRs of theheavy chain variable region, without an associated light chain moiety;and multispecific antibodies formed from antibody fragments. Suchfragments and derivatives and methods of preparing them are well knownin the art. For example, pepsin can be used to digest an antibody belowthe disulfide linkages in the hinge region to produce F(ab)′₂, a dimerof Fab which itself is a light chain joined to V_(H)-C_(H1) by adisulfide bond. The F(ab)′₂ may be reduced under mild conditions tobreak the disulfide linkage in the hinge region, thereby converting theF(ab)′₂ dimer into an Fab′ monomer. The Fab′ monomer is essentially Fabwith part of the hinge region (see Fundamental Immunology (Paul ed., 3ded. 1993)). While various antibody fragments are defined in terms of thedigestion of an intact antibody, one of skill will appreciate that suchfragments may be synthesized de novo either chemically or by usingrecombinant DNA methodology.

In a preferred embodiment, the activating antibodies are non-depletingantibodies, meaning that they bind to NK cells and inhibit NKG2Astimulation, but do not lead to the killing of the NKG2A expressingcell. The ability to kill NKG2A expressing cells can be assessed usingstandard methods, including in vitro assays to ensure that theantibodies are not cytotoxic, directly killing bound cells, as well asin vivo assays in which the antibodies are administered and the leveland activity of NKG2A expressing cells are assessed. In a particularlypreferred embodiment, as described supra, antibodies will be used thatare not recognized (or only poorly recognized) by Fc receptors.Accordingly, preferred antibodies include IgG4, fragments such as Fab orF(ab′)2, or any other IgG, IgE, IgM, etc. of which the Fc portion hasbeen modified to reduce or eliminate binding by Fc receptors (see, e.g.,WO03101485, the entire disclosure of which is herein incorporated byreference).

The preparation of monoclonal or polyclonal antibodies is well known inthe art, and any of a large number of available techniques can be used(see, e.g., Kohler & Milstein, Nature 256:495-497 (1975); Kozbor et al.,Immunology Today 4: 72 (1983); Cole et al., pp. 77-96 in MonoclonalAntibodies and Cancer Therapy (1985)). Techniques for the production ofsingle chain antibodies (U.S. Pat. No. 4,946,778) can be adapted toproduce antibodies to desired polypeptides, e.g., NKG2A. Also,transgenic mice, or other organisms such as other mammals, may be usedto express humanized, chimeric, or similarly-modified antibodies.Alternatively, phage display technology can be used to identifyantibodies and heteromeric Fab fragments that specifically bind toselected antigens (see, e.g., McCafferty et al., Nature 348:552-554(1990); Marks et al., Biotechnology 10:779-783 (1992)). In oneembodiment, the method comprises selecting, from a library orrepertoire, a monoclonal antibody or a fragment or derivative thereofthat cross reacts with an NKG2A receptor polypeptide. For example, therepertoire may be any (recombinant) repertoire of antibodies orfragments thereof, optionally displayed by any suitable structure (e.g.,phage, bacteria, synthetic complex, etc.).

The step of immunizing a non-human mammal with an antigen may be carriedout in any manner well known in the art for (see, for example, E. Harlowand D. Lane, Antibodies: A Laboratory Manual, Cold Spring HarborLaboratory Press, Cold Spring Harbor, N.Y. (1988)). Generally, theimmunogen is suspended or dissolved in a buffer, optionally with anadjuvant, such as complete Freund's adjuvant. Methods for determiningthe amount of immunogen, types of buffers and amounts of adjuvant arewell known to those of skill in the art and are not limiting in any wayon the present invention.

Similarly, the location and frequency of immunization sufficient tostimulate the production of antibodies is also well known in the art. Ina typical immunization protocol, the non-human animals are injectedintraperitoneally with antigen on day 1 and again about a week later.This is followed by recall injections of the antigen around day 20,optionally with adjuvant such as incomplete Freund's adjuvant. Therecall injections are performed intravenously and may be repeated forseveral consecutive days. This is followed by a booster injection at day40, either intravenously or intraperitoneally, typically withoutadjuvant. This protocol results in the production of antigen-specificantibody-producing B cells after about 40 days. Other protocols may alsobe utilized as long as they result in the production of B cellsexpressing an antibody directed to the antigen used in immunization.

In another embodiment, lymphocytes from an unimmunized non-human mammalare isolated, grown in vitro, and then exposed to the immunogen in cellculture. The lymphocytes are then harvested and the fusion stepdescribed below is carried out.

For monoclonal antibodies, which are preferred for the purposes of thepresent invention, the next step is the isolation of cells, e.g.,lymphocytes, splenocytes, or B cells, from the immunized non-humanmammal and the subsequent fusion of those splenocytes, B cells, orlymphocytes with an immortalized cell in order to form anantibody-producing hybridoma. Accordingly, the term “preparingantibodies from an immunized animal,” as used herein, includes obtainingB-cells/splenocytes/lymphocytes from an immunized animal and using thosecells to produce a hybridoma that expresses antibodies, as well asobtaining antibodies directly from the serum of an immunized animal. Theisolation of splenocytes, e.g., from a non-human mammal is well-known inthe art and, e.g., involves removing the spleen from an anesthetizednon-human mammal, cutting it into small pieces and squeezing thesplenocytes from the splenic capsule and through a nylon mesh of a cellstrainer into an appropriate buffer so as to produce a single cellsuspension. The cells are washed, centrifuged and resuspended in abuffer that lyses any red blood cells. The solution is again centrifugedand remaining lymphocytes in the pellet are finally resuspended in freshbuffer.

Once isolated and present in single cell suspension, theantibody-producing cells are fused to an immortal cell line. This istypically a mouse myeloma cell line, although many other immortal celllines useful for creating hybridomas are known in the art. Preferredmurine myeloma lines include, but are not limited to, those derived fromMOPC-21 and MPC-11 mouse tumors available from the Salk Institute CellDistribution Center, San Diego, Calif. U.S.A., X63 Ag8653 and SP-2 cellsavailable from the American Type Culture Collection, Rockville, Md.U.S.A. The fusion is effected using polyethylene glycol or the like. Theresulting hybridomas are then grown in selective media that contains oneor more substances that inhibit the growth or survival of the unfused,parental myeloma cells. For example, if the parental myeloma cells lackthe enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT orHPRT), the culture medium for the hybridomas typically will includehypoxanthine, aminopterin, and thymidine (HAT medium), which substancesprevent the growth of HGPRT-deficient cells.

The hybridomas can be grown on a feeder layer of macrophages. Themacrophages are preferably from littermates of the non-human mammal usedto isolate splenocytes and are typically primed with incomplete Freund'sadjuvant or the like several days before plating the hybridomas. Fusionmethods are described (e.g., in Goding, “Monoclonal Antibodies:Principles and Practice,” pp. 59-103 (Academic Press, 1986), thedisclosure of which is herein incorporated by reference).

The cells are allowed to grow in the selection media for sufficient timefor colony formation and antibody production. This is usually between 7and 14 days. The hybridoma colonies are then assayed for the productionof antibodies that specifically recognize the desired substrate, e.g.NKG2A. The assay is typically a colorimetric ELISA-type assay, althoughany assay may be employed that can be adapted to the wells in which thehybridomas are grown. Other assays include immunoprecipitation andradioimmunoassay. The wells positive for the desired antibody productionare examined to determine if one or more distinct colonies are present.If more than one colony is present, the cells may be recloned and grownto ensure that only a single cell has given rise to the colony producingthe desired antibody. Positive wells with a single apparent colony aretypically recloned and re-assayed to ensure that only one monoclonalantibody is being detected and produced.

Hybridomas that are confirmed to be producing a monoclonal antibody ofthis invention are then grown up in larger amounts in an appropriatemedium, such as DMEM or RPMI-1640. Alternatively, the hybridoma cellscan be grown in vivo as ascites tumors in an animal.

After sufficient growth to produce the desired monoclonal antibody, thegrowth media containing monoclonal antibody (or the ascites fluid) isseparated away from the cells and the monoclonal antibody presenttherein is purified. Purification is typically achieved by gelelectrophoresis, dialysis, chromatography using protein A or proteinG-Sepharose, or an anti-mouse Ig linked to a solid support such asagarose or Sepharose beads (all described, for example, in the AntibodyPurification Handbook, Amersham Biosciences, publication No. 18-1037-46,Edition AC, the disclosure of which is hereby incorporated byreference). The bound antibody is typically eluted from proteinA/protein G columns by using low pH buffers (glycine or acetate buffersof pH 3.0 or less) with immediate neutralization of antibody-containingfractions. These fractions are pooled, dialyzed, and concentrated asneeded.

In preferred embodiments, the DNA encoding an antibody that binds adeterminant present on the NKG2A immunogen is isolated from thehybridoma and placed in an appropriate expression vector fortransfection into an appropriate host. The host is then used for therecombinant production of the antibody, variants thereof, activefragments thereof, or humanized or chimeric antibodies comprising theantigen recognition portion of the antibody. Preferably, the DNA used inthis embodiment encodes an antibody that recognizes a determinantpresent on NKG2A receptors on NK cells, such as NK cells taken from apatient with an autoimmune or inflammatory disorder.

DNA encoding the monoclonal antibodies of the invention can be readilyisolated and sequenced using conventional procedures (e.g., by usingoligonucleotide probes that are capable of binding specifically to genesencoding the heavy and light chains of murine antibodies). Onceisolated, the DNA can be placed into expression vectors, which are thentransfected into host cells such as E. coli cells, simian COS cells,Chinese hamster ovary (CHO) cells, or myeloma cells that do nototherwise produce immunoglobulin protein, to obtain the synthesis ofmonoclonal antibodies in the recombinant host cells. Recombinantexpression in bacteria of DNA encoding the antibody is well known in theart (see, for example, Skerra et al. (1993) Curr. Op. Immunol. 5:256;and Pluckthun (1992) Immunol. Revs. 130:151). Antibodies may also beproduced by selection of combinatorial libraries of immunoglobulins, asdisclosed for instance in Ward et al. (1989) Nature 341:544.

In a specific embodiment, the antibody binds essentially the sameepitope or determinant as one of monoclonal antibodies Z199 or Z270. Inone preferred embodiment, the monoclonal antibody comprises the Fab orF(ab)₂ portion of Z270. According to another preferred embodiment, themonoclonal antibody comprises the three CDRs of the variable heavy chainregion of Z270 (CDR1=amino acids 31 to 35 of SEQ ID NO:2; CDR2=aminoacids 50 to 66 of SEQ ID NO:2; CDR3=amino acids 99-108 of SEQ ID NO:2).More preferred is a monoclonal antibody that comprises the variableheavy chain region of Z270 (Z270VH; SEQ ID NO:2). Even more preferred isa monoclonal antibody that comprises the variable heavy chain region ofZ270 and is transcribed and translated from a nucleotide sequencecomprising chZ270VH (SEQ ID NO:3). According to another preferredembodiment, the monoclonal antibody comprises the three CDRs of thevariable light chain region of Z270 (CDR1=amino acids 24 to 34 of SEQ IDNO:6; CDR2=amino acids 50 to 56 of SEQ ID NO:6; CDR3=amino acids 89-95of SEQ ID NO:6). More preferred is a monoclonal antibody that comprisesthe variable light chain region of Z270 (SEQ ID NO:6). Even morepreferred is a monoclonal antibody that comprises the variable lightchain region of Z270 and is transcribed and translated from a nucleotidesequence comprising chZ270VK (SEQ ID NO:7). In yet another preferredembodiment the antibody is Z270. Z270 was deposited on Dec. 22, 2005 atthe Collection Nationale de Culture de Microorganismes, InstitutePasteur, 25, Rue du Docteur Roux, F-75725 Paris, France, under accessionnumber I-3549.

Both activating and inhibitory monoclonal antibodies against NKG2A willgenerally be modified so as to make them suitable for therapeutic use inhumans. For example, they may be humanized, chimerized, or selected froma library of human antibodies using methods well known in the art. Suchhuman-suitable antibodies can be used directly in the presenttherapeutic methods, or can be further derivatized into cytotoxicantibodies, as described infra, for use in the methods.

In one preferred embodiment, the DNA of a hybridoma producing anantibody of this invention, e.g. an antibody that binds to substantiallythe same epitope as Z199 or Z270, can be modified prior to insertioninto an expression vector, for example, by substituting the codingsequence for human heavy- and light-chain constant domains in place ofthe homologous non-human sequences (e.g., Morrison et al. (1984) PNAS81:6851), or by covalently joining to the immunoglobulin coding sequenceall or part of the coding sequence for a non-immunoglobulin polypeptide.In that manner, “chimeric” or “hybrid” antibodies are prepared that havethe binding specificity of the original antibody. Typically, suchnon-immunoglobulin polypeptides are substituted for the constant domainsof an antibody of the invention.

In a preferred embodiment, the antibody comprises the variable heavychain region of Z270 fused (SEQ ID NO:2) to a human heavy chain constantregion. In one preferred embodiment, the human heavy chain constantregion is a IgG4 constant region. In another preferred embodiment, thehuman heavy chain constant region is a IgG1 constant region, preferablya human IgG1m(-1, -2, -3) constant region. Preferably, such a humanheavy chain constant region-containing antibody is transcribed andtranslated from a nucleotide sequence comprising chZ270VH (SEQ ID NO:3).

In another preferred embodiment, the antibody comprises the variablelight chain region of Z270 fused (SEQ ID NO:6) to a human light chainconstant region. More preferred is an antibody that comprises thevariable light chain region of Z270 fused to the human kappa (k3) lightchain constant region. Preferably, such a human light chain constantregion-containing antibody is transcribed and translated from anucleotide sequence comprising chZ270VK (SEQ ID NO:7).

Even more preferred is an antibody comprising both 270VK fused to ahuman light chain constant region and 270VK fused to a human heavy chainconstant region. Preferably, the light chain constant region is a kappa(k3) constant region and the heavy chain constant region is selectedfrom IgG4 or IgG1m(-1, -2, -3). Also, preferably, each of the heavy andlight chains of the antibody are transcribed from a nucleotide sequencecomprising chZ270VH (SEQ ID NO:3) and a nucleotide sequence comprisingchZ270VK (SEQ ID NO:7), respectively.

In one particularly preferred embodiment, the antibody of this inventionis humanized. “Humanized” forms of antibodies according to thisinvention are specific chimeric immunoglobulins, immunoglobulin chainsor fragments thereof (such as Fv, Fab, Fab′, F(ab′) 2, or otherantigen-binding subsequences of antibodies) which contain minimalsequence derived from the murine or other non-human immunoglobulin. Forthe most part, humanized antibodies are human immunoglobulins (recipientantibody) in which residues from a complementary-determining region(CDR) of the recipient are replaced by residues from a CDR of theoriginal antibody (donor antibody) while maintaining the desiredspecificity, affinity, and capacity of the original antibody. In someinstances, Fv framework residues of the human immunoglobulin may bereplaced by corresponding non-human residues. Furthermore, humanizedantibodies can comprise residues that are not found in either therecipient antibody or in the imported CDR or framework sequences. Thesemodifications are made to further refine and optimize antibodyperformance. In general, the humanized antibody will comprisesubstantially all of at least one, and typically two, variable domains,in which all or substantially all of the CDR regions correspond to thoseof the original antibody and all or substantially all of the FR regionsare those of a human immunoglobulin consensus sequence. For furtherdetails see Jones et al. (1986) Nature 321: 522; Reichmann et al. (1988)Nature 332: 323; Verhoeyen et al. (1988) Science 239:1534 (1988); Presta(1992) Curr. Op. Struct. Biol. 2:593; each of which is hereinincorporated by reference in its entirety.

The choice of human variable domains, both light and heavy, to be usedin making the humanized antibodies is very important to reduceantigenicity. According to the so-called “best-fit” method, the sequenceof the variable domain of an antibody of this invention is screenedagainst the entire library of known human variable-domain sequences. Thehuman sequence which is closest to that of the mouse is then accepted asthe human framework (FR) for the humanized antibody (Sims et al. (1993)J. Immun., 151:2296; Chothia and Lesk (1987) J. Mol. Biol. 196:901).Another method uses a particular framework from the consensus sequenceof all human antibodies of a particular subgroup of light or heavychains. The same framework can be used for several different humanizedantibodies (Carter et al. (1992) PNAS 89:4285; Presta et al. (1993) J.Immunol. 51:1993)).

It is further important that antibodies be humanized while retainingtheir high affinity for NKG2A, preferably human and non-human primateNKG2A, and other favorable biological properties. To achieve this goal,according to a preferred method, humanized antibodies are prepared by aprocess of analysis of the parental sequences and various conceptualhumanized products using three-dimensional models of the parental andhumanized sequences. Three-dimensional immunoglobulin models arecommonly available and are familiar to those skilled in the art.Computer programs are available which illustrate and display probablethree-dimensional conformational structures of selected candidateimmunoglobulin sequences. Inspection of these displays permits analysisof the likely role of the residues in the functioning of the candidateimmunoglobulin sequence, i.e., the analysis of residues that influencethe ability of the candidate immunoglobulin to bind its antigen. In thisway, FR residues can be selected and combined from the consensus andimport sequences so that the desired antibody characteristic, such asincreased affinity for the target antigen(s), is achieved. In general,the CDR residues are directly and most substantially involved ininfluencing antigen binding.

In preferred examples, the invention provides human or humanizedactivating anti-NKG2A antibodies having a half-life of at least 5, 6, 8,9, 10, 15 or 20 days, which do not substantially bind human FcgammaRIIIa(CD16). More preferably, the activating anti-NKG2A antibody is ahumanized antibody and completely competes with a Z199 or Z270 antibodyfor binding to human NKG2A. For the purpose of illustration withpreferred antibodies suitable for use according to the methods herein, aZ199 or Z270 antibody can be used to prepare a humanized antibody.Preferred humanized antibodies according to the invention comprise ahuman framework, at least one CDR from a non-human antibody, and inwhich any constant region present is substantially identical to a humanimmunoglobulin constant region, e.g., at least about 60-90%, preferablyat least 95% identical. Hence, all parts of a humanized antibody, exceptpossibly the CDR's, are substantially identical to corresponding partsof one or more native human antibody sequences. In some instances, thehumanized antibody, in addition to CDRs from a non-human antibody, wouldinclude additional non-human residues in the human framework region.

The design of humanized antibodies can be carried out as follows. Whenan amino acid falls under the following categories, the framework aminoacid of a human antibody to be used (acceptor antibody) is replaced by aframework amino acid from a CDR-providing non-human antibody (donorantibody): (a) the amino acid in the human framework region of theacceptor antibody is unusual for human antibody at that position,whereas the corresponding amino acid in the donor antibody is typicalfor human antibody in that position; (b) the position of the amino acidis immediately adjacent to one of the CDR's; or (c) the amino acid iscapable of interacting with the CDR's in a tertiary structure antibodymodel (see, C. Queen et al. Proc. Natl. Acad. Sci. USA 86, 10029 (1989),and Co et al., Proc. Natl. Acad. Sci. USA 88, 2869 (1991) thedisclosures of which are incorporated herein by reference).

For further detailed description of the production of humanizedantibody, See Queen et al., op. cit. and Co et al, op. cit. and U.S.Pat. Nos. 5,585,089; 5,693,762, 5,693,761, and 5,530,101, thedisclosures of which are incorporated herein by reference. Usually, theCDR regions in humanized antibodies are substantially identical, andmore usually, identical to the corresponding CDR regions in the mouseantibody from which they were derived. Although not usually desirable,it is sometimes possible to make one or more conservative amino acidsubstitutions of CDR residues without appreciably affecting the bindingaffinity of the resulting humanized antibody. Occasionally,substitutions of CDR regions can enhance binding affinity. Other thanfor the specific amino acid substitutions discussed above, the frameworkregions of humanized antibodies are usually substantially identical, andmore usually, identical to the framework regions of the human antibodiesfrom which they were derived. Of course, many of the amino acids in theframework region make little or no direct contribution to thespecificity or affinity of an antibody. Thus, many individualconservative substitutions of framework residues can be toleratedwithout appreciable change of the specificity or affinity of theresulting humanized antibody. The antigen binding region of thehumanized antibody (the non-human portion) can be derived from anantibody of nonhuman origin, referred to as a donor antibody, havingspecificity for NKG2A. For example, a suitable antigen binding regioncan be derived from Z199 or Z270 monoclonal antibodies. Other sourcesinclude NKG2A-specific (blocking) antibodies obtained from nonhumansources, such as rodent (e.g., mouse and rat), rabbit, pig, goat ornon-human primate (e.g., monkey) or camelid animals (e.g., camels andllamas). Additionally, other polyclonal or monoclonal antibodies, suchas antibodies which bind to the same or similar epitope as Z199 or Z270antibodies, can be made (e.g., Kohler et al., Nature, 256:495-497(1975); Harlow et al., 1988, Antibodies: A Laboratory Manual (ColdSpring Harbor, N.Y.); and Current Protocols in Molecular Biology, Vol. 2(Supplement 27, Summer '94), Ausubel et al., Eds. (John Wiley & Sons:New York, N.Y.), Chapter 11 (1991)).

In one embodiment, the humanized antibody having binding specificity forhuman and non-human primate NKG2A comprises at least one CDR of nonhumanorigin. For example, a humanized antibody having a binding specificityfor human and non-human primate NKG2A comprises a heavy chain and alight chain. The light chain can comprise a CDR derived from an antibodyof nonhuman origin which binds NKG2A and a FR derived from a light chainof human origin. For example, the light chain can comprise CDR1, CDR2and/or CDR3 which have the amino acid sequence similar or substantiallythe same as that of the respective CDR of any one of the Z199 or Z270antibodies such that the antibody specifically binds to the human andnon-human primate NKG2A. The heavy chain can comprise a CDR derived froman antibody of nonhuman origin which binds NKG2A and a FR derived from aheavy chain of human origin. For example, the heavy chain can compriseCDR1, CDR2 and CDR3 which have the amino acid sequence set forth belowor an amino acid similar or substantially the same as that of therespective CDR of the Z199 or Z270 antibodies such that the antibodyspecifically binds to the human and non-human primate NKG2A.

An embodiment of the invention is a humanized antibody whichspecifically binds to human and non-human primate NKG2A and comprises ahumanized light chain comprising three light chain CDRs from a Z199 orZ270 antibody and a light chain variable region framework sequence froma human antibody light chain. The invention further comprises ahumanized heavy chain that comprises three heavy chain CDRs from a Z199or Z270 antibody and a heavy chain variable region framework sequencefrom a human antibody heavy chain.

The portion of the humanized antibody or antibody chain which is ofhuman origin (the human portion) can be derived from any suitable humanantibody or antibody chain. For example, a human constant region orportion thereof, if present, can be derived from the kappa or lambdalight chains, and/or the gamma (e.g., gamma1, gamma2, gamma3, gamma4),μ, alpha (e.g., alpha1, alpha2), delta or epsilon heavy chains of humanantibodies, including allelic variants. A particular constant region,such as IgG2b or IgG4, variants or portions thereof can be selected totailor effector function. The latter constant regions, or portionsthereof are particularly preferred in that they do not substantiallybind FcgammaIIIa receptor on NK cells (CD16) and therefore do notsubstantially induce ADCC mediated lysis of NK effectors to which theanti-NKG2A antibodies of the invention are bound. For example, a mutatedconstant region, also referred to as a “variant,” can be incorporatedinto a fusion protein to minimize binding to Fc receptors and/or abilityto fix complement (see e.g., Winter et al., U.S. Pat. No. 5,648,260;Morrison et al., WO 89/07142; Morgan et al., WO 94/29351). In addition,a mutated IgG2 Fc domain can be created that reduces the mitogenicresponse, as compared to natural Fc regions (see e.g., Tso et al., U.S.Pat. No. 5,834,597, the teachings of which are incorporated by referenceherein in their entirety). If present, human FRs are preferably derivedfrom a human antibody variable region having sequence similarity to theanalogous or equivalent region of the antigen binding region donor.Other sources of FRs for portions of human origin of a humanizedantibody include human variable consensus sequences (see, Kettleborough,C. A. et al., Protein Engineering 4:773-783 (1991); Queen et al., U.S.Pat. Nos. 5,585,089, 5,693,762 and 5,693,761, the teachings of all ofwhich are incorporated by reference herein in their entirety). Forexample, the sequence of the antibody or variable region used to obtainthe nonhuman portion can be compared to human sequences as described inKabat, E. A., et al., Sequences of Proteins of Immunological Interest,Fifth Edition, U.S. Department of Health and Human Services, U.S.Government Printing Office (1991). In a preferred embodiment, the FRs ofa humanized antibody chain are derived from a human variable regionhaving at least about 60% overall sequence identity, and preferably atleast about 80% overall sequence identity, with the variable region ofthe nonhuman donor (e.g., Z199 or Z270 antibody).

The phrase “substantially identical,” in context of two nucleic acids orpolypeptides (e.g., DNAs encoding a humanized antibody or the amino acidsequence of the humanized antibody) refers to two or more sequences orsubsequences that have at least about 80%, most preferably 90-95% orhigher nucleotide or amino acid residue identity, when compared andaligned for maximum correspondence, as measured using the followingsequence comparison method and/or by visual inspection. Such“substantially identical” sequences are typically considered to behomologous. Preferably, the “substantial identity” exists over a regionof the sequences that is at least about 50 residues in length, morepreferably over a region of at least about 100 residues, and mostpreferably the sequences are substantially identical over at least about150 residues, or over the full length of the two sequences to becompared. As described below, any two antibody sequences can only bealigned in one way, by using the numbering scheme in Kabat. Therefore,for antibodies, percent identity has a unique and well-defined meaning.

Amino acids from the variable regions of the mature heavy and lightchains of antibodies are designated Hx and Lx respectively, where x is anumber designating the position of an amino acid according to the schemeof Kabat, Sequences of Proteins of Immunological Interest (NationalInstitutes of Health, Bethesda, Md., 1987 and 1991). Kabat lists manyamino acid sequences for antibodies for each subgroup, and lists themost commonly occurring amino acid for each residue position in thatsubgroup. Kabat uses a method for assigning a residue number to eachamino acid in a listed sequence, and this method for assigning residuenumbers has become standard in the field. Kabat's scheme is extendibleto other antibodies not included in his compendium by aligning theantibody in question with one of the consensus sequences in Kabat. Theuse of the Kabat numbering system readily identifies amino acids atequivalent positions in different antibodies. For example, an amino acidat the L50 position of a human antibody occupies the equivalent positionto an amino acid position L50 of a mouse antibody. From N-terminal toC-terminal, both light and heavy chain variable regions comprisealternating framework and (CDRs): FR1, CDR1, FR2, CDR2, FR3, CDR3 andFR4. The assignment of amino acids to each region is in accordance withthe definitions of Kabat (1987) and (1991), supra and/or Chothia & Lesk,J. Mol. Biol. 196:901-917 (1987); Chothia et al., Nature 342:878-883(1989).

Binding and/or adhesion assays or other suitable methods can also beused in procedures for the identification and/or isolation of humanizedantibodies (e.g., from a library) with the requisite specificity(competition assays for example).

The antibody portions of nonhuman and human origin for use in theinvention include light chains, heavy chains and portions of light andheavy chains. These antibody portions can be obtained or derived fromantibodies (e.g., by de novo synthesis of a portion), or nucleic acidsencoding an antibody or chain thereof having the desired property (e.g.,binds NKG2A, sequence similarity, for example with the Z199 or Z270antibody) can be produced and expressed. Humanized antibodies comprisingthe desired portions (e.g., antigen binding region, CDR, FR, C region)of human and nonhuman origin can be produced using synthetic and/orrecombinant nucleic acids to prepare genes (e.g., cDNA) encoding thedesired humanized chain. To prepare a portion of a chain, one or morestop codons can be introduced at the desired position. For example,nucleic acid sequences coding for newly designed humanized variableregions can be constructed using PCR mutagenesis methods to alterexisting DNA sequences (see e.g., Kamman, M., et al., Nucl. Acids Res.17:5404 (1989)). PCR primers coding for the new CDRs can be hybridizedto a DNA template of a previously humanized variable region which isbased on the same, or a very similar, human variable region (Sato, K.,et al., Cancer Research 53:851-856 (1993)). If a similar DNA sequence isnot available for use as a template, a nucleic acid comprising asequence encoding a variable region sequence can be constructed fromsynthetic oligonucleotides (see e.g., Kolbinger, F., Protein Engineering8:971-980 (1993)). A sequence encoding a signal peptide can also beincorporated into the nucleic acid (e.g., on synthesis, upon insertioninto a vector). If the natural signal peptide sequence is unavailable, asignal peptide sequence from another antibody can be used (see, e.g.,Kettleborough, C. A., Protein Engineering 4:773-783 (1991)). Using thesemethods, methods described herein or other suitable methods, variantscan be readily produced. In one embodiment, cloned variable regions canbe mutagenized, and sequences encoding variants with the desiredspecificity can be selected (e.g., from a phage library; see e.g.,Krebber et al., U.S. Pat. No. 5,514,548; Hoogengoom et al., WO 93/06213,published Apr. 1, 1993)).

The invention also relates to isolated and/or recombinant (including,e.g., essentially pure) nucleic acids comprising sequences which encodea humanized antibody or humanized antibody light or heavy chain of thepresent invention.

Human antibodies may also be produced according to various othertechniques, such as by using, for immunization, other transgenic animalsthat have been engineered to express a human antibody repertoire. Inthis technique, elements of the human heavy and light chain loci areintroduced into mice or other animals with targeted disruptions of theendogenous heavy chain and light chain loci (see, e.g., Jakobovitz etal. (1993) Nature 362:255; Green et al. (1994) Nature Genet. 7:13;Lonberg et al. (1994) Nature 368:856; Taylor et al. (1994) Int. Immun.6:579, the entire disclosures of which are herein incorporated byreference). Alternatively, human antibodies can be constructed bygenetic or chromosomal transfection methods, or through the selection ofantibody repertoires using phage display methods. In this technique,antibody variable domain genes are cloned in-frame into either a majoror minor coat protein gene of a filamentous bacteriophage, and displayedas functional antibody fragments on the surface of the phage particle.Because the filamentous particle contains a single-stranded DNA copy ofthe phage genome, selections based on the functional properties of theantibody also result in selection of the gene encoding the antibodyexhibiting those properties. In this way, the phage mimics some of theproperties of the B cell (see, e.g., Johnson et al. (1993) Curr OpStruct Biol 3:5564-571; McCafferty et al. (1990) Nature 348:552-553, theentire disclosures of which are herein incorporated by reference). Humanantibodies may also be generated by in vitro activated B cells (see,e.g., U.S. Pat. Nos. 5,567,610 and 5,229,275, the disclosures of whichare incorporated in their entirety by reference).

In one embodiment, “humanized” monoclonal antibodies are made using ananimal such as a XenoMouse® (Abgenix, Fremont, Calif.) for immunization.A XenoMouse is a murine host that has had its immunoglobulin genesreplaced by functional human immunoglobulin genes. Thus, antibodiesproduced by this mouse or in hybridomas made from the B cells of thismouse are already humanized. The XenoMouse is described in U.S. Pat. No.6,162,963, which is herein incorporated in its entirety by reference. Ananalogous method can be achieved using a HuMAb-Mouse™ (Medarex).

The antibodies of the present invention may also be derivatized to“chimeric” antibodies (immunoglobulins) in which a portion of the heavyand/or light chain is identical with or homologous to correspondingsequences in the original antibody, while the remainder of the chain(s)is identical with or homologous to corresponding sequences in antibodiesderived from another species or belonging to another antibody class orsubclass, as well as fragments of such antibodies, so long as theyexhibit the desired biological activity (see, e.g., Morrison et al.(1984) PNAS 81:6851; U.S. Pat. No. 4,816,567).

In another embodiment the invention provides any of the antibodies orfragments thereof described above (whether activating or inhibitory)conjugated to a cytotoxic agent. The term “cytotoxic agent” as usedherein is a molecule that is capable of killing a cell bearing a NKG2Areceptor on its cell surface. The term “conjugated” as used herein meansthat the two agents are either bound to each other through a covalentand/or non-covalent bond, or tethered or otherwise connected to oneanother directly or through a linking moiety.

Any of a large number of toxic moieties or strategies can be used toproduce such cytotoxic antibody conjugates. In certain preferredembodiments, the antibodies will be directly derivatized withradioisotopes or other toxic compounds. In such cases, the labeledmonospecific anti-NKG2A antibody can be injected into the patient, whereit can then bind to and kill cells expressing that target antigen,particularly NK cells, with unbound antibody simply clearing the body.Indirect strategies can also be used, such as the “Affinity EnhancementSystem” (AES) (see, e.g., U.S. Pat. No. 5,256,395; Barbet et al. (1999)Cancer Biother Radiopharm 14:153-166; the entire disclosures of whichare herein incorporated by reference). This particular approach involvesthe use of a radiolabeled hapten and an antibody that recognizes boththe NK cell receptor and the radioactive hapten. In this case, theantibody is first injected into the patient and allowed to bind totarget cells, and then, once unbound antibody is allowed to clear fromthe blood stream, the radiolabeled hapten is administered. The haptenbinds to the antibody-antigen complex on the overproliferating LGL (e.g.NK or T) cells, thereby killing them, with the unbound hapten clearingthe body.

Any type of moiety with a cytotoxic or cytoinhibitory effect can beconjugated to the present antibodies to form a cytotoxic conjugate ofthe present invention and to inhibit or kill specific NK receptorexpressing cells, including radioisotopes, toxic proteins, toxic smallmolecules, such as drugs, toxins, immunomodulators, hormones, hormoneantagonists, enzymes, oligonucleotides, enzyme inhibitors, therapeuticradionuclides, angiogenesis inhibitors, chemotherapeutic drugs, vincaalkaloids, anthracyclines, epidophyllotoxins, taxanes, antimetabolites,alkylating agents, antibiotics, COX-2 inhibitors, SN-38, antimitotics,antiangiogenic and apoptotoic agents, particularly doxorubicin,methotrexate, taxol, CPT-11, camptothecans, nitrogen mustards,gemcitabine, alkyl sulfonates, nitrosoureas, triazenes, folic acidanalogs, pyrimidine analogs, purine analogs, platinum coordinationcomplexes, Pseudomonas exotoxin, ricin, abrin, 5-fluorouridine,ribonuclease (RNase), DNase I, Staphylococcal enterotoxin-A, pokeweedantiviral protein, gelonin, diphtherin toxin, Pseudomonas exotoxin, andPseudomonas endotoxin and others (see, e.g., Remington's PharmaceuticalSciences, 19th Ed. (Mack Publishing Co. 1995); Goodman and Gilman's ThePharmacological Basis of Therapeutics (McGraw Hill, 2001); Pastan et al.(1986) Cell 47:641; Goldenberg (1994) Cancer Journal for Clinicians44:43; U.S. Pat. No. 6,077,499; the entire disclosures of which areherein incorporated by reference). It will be appreciated that a toxincan be of animal, plant, fungal, or microbial origin, or can be createdde novo by chemical synthesis.

The toxins or other compounds can be linked to the antibody directly orindirectly, using any of a large number of available methods. Forexample, an agent can be attached at the hinge region of the reducedantibody component via disulfide bond formation, using cross-linkerssuch as N-succinyl 3-(2-pyridyldithio)proprionate (SPDP), or via acarbohydrate moiety in the Fc region of the antibody (see, e.g., Yu etal. (1994) Int. J. Cancer 56: 244; Wong, Chemistry of ProteinConjugation and Cross-linking (CRC Press 1991); Upeslacis et al.,“Modification of Antibodies by Chemical Methods,” in Monoclonalantibodies: principles and applications, Birch et al. (eds.), pages187-230 (Wiley-Liss, Inc. 1995); Price, “Production and Characterizationof Synthetic Peptide-Derived Antibodies,” in Monoclonal antibodies:Production, engineering and clinical application, Ritter et al. (eds.),pages 60-84 (Cambridge University Press 1995), Cattel et al. (1989)Chemistry today 7:51-58, Delprino et al. (1993) J. Pharm. Sci82:699-704; Arpicco et al. (1997) Bioconjugate Chemistry 8:3; Reisfeldet al. (1989) Antibody, Immunicon. Radiopharrn. 2:217; the entiredisclosures of each of which are herein incorporated by reference).

In one preferred embodiment, the antibody will be derivatized with aradioactive isotope, such as 1-131. Any of a number of suitableradioactive isotopes can be used, including, but not limited to,Indium-111, Lutetium-171, Bismuth-212, Bismuth-213, Astatine-211,Copper-62, Copper-64, Copper-67, Yttrium-90, Iodine-125, Iodine-131,Phosphorus-32, Phosphorus-33, Scandium-47, Silver-111, Gallium-67,Praseodymium-142, Samarium-153, Terbium-161, Dysprosium-166,Holmium-166, Rhenium-186, Rhenium-188, Rhenium-189, Lead-212,Radium-223, Actinium-225, Iron-59, Selenium-75, Arsenic-77,Strontium-89, Molybdenum-99, Rhodium-105, Palladium-109,Praseodymium-143, Promethium-149, Erbium-169, Iridium-194, Gold-198,Gold-199, and Lead-211. In general, the radionuclide preferably has adecay energy in the range of 20 to 6,000 keV, preferably in the ranges60 to 200 keV for an Auger emitter, 100-2,500 keV for a beta emitter,and 4,000-6,000 keV for an alpha emitter. Also preferred areradionuclides that substantially decay with generation ofalpha-particles.

In selecting a cytotoxic moiety for conjugation to the anti-NKG2Aantibody in the present cytotoxic compositions, it is desirable toensure that the moiety will not exert significant in vivo side effectsagainst life-sustaining normal tissues, such as one or more tissuesselected from heart, kidney, brain, liver, bone marrow, colon, breast,prostate, thyroid, gall bladder, lung, adrenals, muscle, nerve fibers,pancreas, skin, or other life-sustaining organ or tissue in the humanbody. The term “significant side effects”, as used herein, refers to anantibody, ligand or antibody conjugate, that, when administered in vivo,will produce only negligible or clinically manageable side effects, suchas those normally encountered during chemotherapy.

In a somewhat related embodiment, the invention also provides anantibody of this invention conjugated to a detectable marker. The term“detectable marker” as used herein refers to any molecule that can bequantitatively or qualitatively observed or measured. Examples ofdetectable markers useful in the conjugated antibodies of this inventionare radioisotopes, fluorescent dyes, or a member of a complementarybinding pair, such as a member of any one of: an antigen/antibody (otherthan an antibody to NKG2A); lectin/carbohydrate; avidin/biotin;receptor/ligand; or molecularly imprinted polymer/print moleculesystems.

The detectable marker conjugated antibodies of this invention may beused to detect the binding of the antibody to NKG2A, either in vitro orin vivo. Such conjugates may also be utilized to detect the binding ofanother molecule to NKG2A in a competition-type experiment. In an invivo setting, the detectable marker-antibody conjugate of this inventionmay be used to monitor the efficacy of treatment of a patient with aNKG2A antibody composition of this invention, by ex vivo detection ofthe detectable marker (e.g., via whole body scans or the like) or bydetection in a biological material (e.g., blood, biopsied tissue, otherbodily fluids, skin scrapings, etc.) obtained from the patient. Thedetection of the marker in various biological material will becorrelated with the presence of the therapeutic antibody in saidmaterial.

In a related embodiment the invention provides a kit comprising, inseparate vessels: a detectable marker-anti-NKG2A antibody conjugate; andan NKG2A-containing material. An NKG2A-containing material may beisolated NKG2A, a fragment of NKG2A comprising an epitope to which ananti-NKG2A antibody of this invention binds, or a cell that expressesNKG2A on its cell surface.

Evaluation of Anti-Human NKG2A Antibodies in Nonhuman Primates

In a preferred series of embodiments, the activity of an anti-NKG2Aantibody of this invention will be assessed in vivo in a nonhumanprimate. Such embodiments can be carried out for any of a wide varietyof reasons. In view of the crossreactivity between human NKG2A and NKG2Afrom nonhuman primates, and in view of the physiological similaritiesamong primates, administering antibodies that recognize human NKG2A tononhuman primates allows the antibodies to be assessed in vivo for manyaspects including, but not limited to, ability to modulate the activityof cells expressing NKG2A (e.g. NK cells), side effects produced,toxicity, pharmacodynamics, pharmacokinetics, bioavailability,half-life, optimal dose or frequency of administration, optimalformulations including combinations with other therapeutic agents, orany other property that may be measured to determine the efficacy,safety, or optimal administration of the antibodies. Methods ofassessing candidate therapeutic compounds in vivo are well known in theart, and are described, e.g., in The Merck Manual of Diagnosis andTherapy, 17^(th) edition, Remington's Pharmaceutical Sciences, 20^(th)edition, the entire disclosures of which are herein incorporated byreference.

Any nonhuman primate can be used for the herein-described methods,including apes, monkeys, and prosimians. Preferred primates include theRhesus monkey (Macacus mulatta), African green monkey (Chlorocebusaethiops), Marmoset (Callithrix jacchus), Saïmiri (Saimiri sciureus),cynomolgus, and Baboon (Papio hamadryas). In another preferredembodiment, the primate is not an ape, e.g. is a primate other than achimpanzee. Non-human primates are commonly used in safety and efficacyassays for candidate human therapeutic agents, and their care,administration, biology, and other relevant features are well known tothose in the art. In one embodiment, prior to the administration of anyantibody to any nonhuman primate (or the use of tissue, cells, orproteins from a nonhuman primate in any assay), the crossreactivity ofthe candidate anti-human NKG2A antibodies with NKG2A from the nonhumanprimate will be confirmed.

In certain embodiments, the nonhuman primates will serve as a model fora disease or condition that could be treated by an NKG2A-modulatingcompound. For example, models of autoimmune disorders, allergies,cancers, or infectious diseases can be used, e.g. to assess the abilityof the antibodies to treat or alleviate the symptoms of the diseases orconditions. While in no way limiting for the practice of the presentinvention, certain nonhuman primates are particularly useful forstudying particular types of diseases or conditions. For example,marmosets have served as model animals for the study of immunity and ofcardiovascular diseases, saimiri for the study of infectious diseases,macaques (including rhesus monkeys) for the study of pharmacology andtoxicology of specific compounds, and baboons as a model for surgicalstudies, transplants, and biomaterials.

In one embodiment, anti-NKG2A antibodies are administered to a nonhumanprimate to assess the efficacy of the antibodies in binding to and/ormodulating NKG2A activity. In such embodiments, the antibodies can beadministered in any dose, frequency, or formulation, and indeed suchfactors can be varied to assess their relative influence over theefficacy. Efficacy of the antibodies can be assessed in any of a largevariety of ways. For example, one can assess the in vivo binding of theantibodies to NKG2A or to NKG2A-expressing cells, the in vivo effect ofthe antibodies on the expression of NKG2A on cells, e.g. NK cells, orthe in vivo influence of the antibodies on the activity of NKG2A, e.g.as measured using any of the herein-described assays for NK cellactivity. In such embodiments, an antibody is typically administered toa nonhuman primate and its effects detected, e.g., on biological samplesobtained from the nonhuman primate. Alternatively, certain methods canbe carried out in vitro, where the effects of the antibodies on, e.g.,NKG2A-expressing cells obtained from a nonhuman primate are examined.

To assess the binding of the anti-human NKG2A antibodies, the antibodiescan be directly or indirectly labeled. For example, the antibody can belabeled with a radioisotope prior to administration, and itslocalization within the animal assessed by examining various biologicalsamples (e.g., blood, various tissues or organs, immune-related tissuessuch as bone marrow, spleen, lymphatic system components, or others)obtained at different times after administration. In one preferredembodiment, PBLs are obtained, and the binding of the antibodies to NKcells is determined using, e.g., fluorescently labeled secondaryantibodies, with bound antibodies detected, e.g., by FACS analysis.

Similarly, antibodies can be administered to a nonhuman primate andtheir effect on NKG2A activity assessed. For example, NK cells can beobtained prior and subsequent to administration of an anti-NKG2Aantibody, and the activity, expression of NKG2A, and/or number of thetwo (or more) sets of cells assessed using any standard method.Activating antibodies of this invention that block NKG2A stimulation(and thereby block inhibition of NK cells through the receptor) would beexpected to increase NK cell activity. Inhibitory antibodies of thisinvention that cross-link NKG2A receptors would be expected to decreaseNK cell activity and decrease the number of viable NK cells. Both typesof antibodies that cause altered NK cell activity in the nonhumanprimate would be considered suitable for use in treating disorders inhumans where an increase or a decrease in NK cell activity is desirable.

In another set of embodiments, anti-NKG2A antibodies are administered toa nonhuman primate in order to assess the safety of the antibodies, aswell as their various pharmacokinetic and pharmacodynamic properties.Safety can be assessed in any of a large variety of ways. For example,the overall toxicity of the antibodies can be assessed, by determiningthe median lethal dose (LD50), typically expressed as milligram perkilogram (mg/kg), in which the value 50 refers to the percentage deathamong the animals under study. In addition to determining the LD50,safety can also be assessed by monitoring the animals for any detectableresponses to the administration, including behavioral, physical, orphysiological changes as evidenced by heart rate, blood pressure, etc.Responses can also involve blood and other laboratory based tests toexamine markers indicative of organ function, such as creatine or BUNfor renal function, prothrombin, bilirubin, albumin, or various enzymesto determine hepatic function, or others (see, e.g., The Merck Manual ofDiagnosis and Therapy, 17^(th) edition, herein incorporated byreference).

Methods for in vivo pharmacokinetic and pharmacodynamic assessment ofthe antibodies are standard and well known in the art (see, e.g., He etal. (1998) J. Immunol. 160:1029-1035; Alyanakian et al. (2003) VoxSanguinis 84:188-192, Sharma et al. (2000) WET 293:33-41, the entiredisclosures of which are herein incorporated by reference). Such assayswould typically involve administering anti-NKG2A antibodies to anonhuman primate and, at various times after administration, examiningthe level (in plasma and other tissues), distribution, binding,stability, and other properties of the antibodies. Such assays arecritical components of pre-clinical studies and, by determining the invivo half life, distribution, bioavailability, etc. of the antibodies,help determine the therapeutic window and thus proper administrationregimens (e.g. frequency and dose of administration) that will allowoptimal targeting of NK expressing cells by the administered antibodies.

In conjunction with studies of the efficacy, safety, pharmacodynamicsand pharmacokinetics of anti-NKG2A antibodies, a variety of formulationsand administration regimens can also be systematically tested to obtainoptimal efficacy and safety for anti-human NKG2A antibodies. Forexample, the therapeutic window (the range of plasma concentrations ofthe antibodies that have a high probability of therapeutic success) canbe determined, as well as those regimens and formulations that areoptimally safe and effective in targeting NKG2A and modulating NK cellactivity in vivo. For example, a given antibody can be administeredevery 1, 2, 3, 4, 5, or 6 days, or every 1, 2, 3, or 4 weeks, etc., andthe safety, efficacy, kinetic, etc. parameters examined. Similarly, thedose of the antibody administered at any one time can be varied and thesame parameters examined, or any combination of dose and frequency ofadministration can be tested. Further, different formulations, e.g.,compositions including different excipients, different combinations ofanti-NKG2A antibodies, or different combinations of NKG2A antibodieswith other therapeutic agents (depending on the condition that would betreated, e.g. a chemotherapeutic agent to treat cancer) can be tested innonhuman primates. Also, different routes of administration, e.g.intravenous, pulmonary, topical, etc., can be compared. Such methods ofvarying administration parameters are well known to those of skill inthe art.

Pharmaceutical Compositions

The invention also provides compositions, e.g., pharmaceuticalcompositions, that comprise any of the present antibodies, includingfragments and derivatives thereof, in any suitable vehicle in aneffective amount and a pharmaceutically acceptable carrier.

Pharmaceutically acceptable carriers that may be used in thesecompositions include, but are not limited to, ion exchangers, alumina,aluminum stearate, lecithin, serum proteins, such as human serumalbumin, buffer substances such as phosphates, glycine, sorbic acid,potassium sorbate, partial glyceride mixtures of saturated vegetablefatty acids, water, salts or electrolytes, such as protamine sulfate,disodium hydrogen phosphate, potassium hydrogen phosphate, sodiumchloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinylpyrrolidone, cellulose-based substances, polyethylene glycol, sodiumcarboxymethylcellulose, polyacrylates, waxes,polyethylene-polyoxypropylene-block polymers and wool fat.

The compositions of the present invention may be administered orally,parenterally, by inhalation spray, topically, rectally, nasally,buccally, vaginally or via an implanted reservoir. The term “parenteral”as used herein includes subcutaneous, intravenous, intramuscular,intra-articular, intra-synovial, intrasternal, intrathecal,intrahepatic, intralesional and intracranial injection or infusiontechniques. For localized disorders such as RA, the compositions willoften be administered topically, e.g., in inflamed joints.

Sterile injectable forms of the compositions of this invention may beaqueous or an oleaginous suspension. These suspensions may be formulatedaccording to techniques known in the art using suitable dispersing orwetting agents and suspending agents. The sterile injectable preparationmay also be a sterile injectable solution or suspension in a non-toxicparenterally acceptable diluent or solvent, for example as a solution in1,3-butanediol. Among the acceptable vehicles and solvents that may beemployed are water, Ringer's solution and isotonic sodium chloridesolution. In addition, sterile, fixed oils are conventionally employedas a solvent or suspending medium. For this purpose, any bland fixed oilmay be employed including synthetic mono- or diglycerides. Fatty acids,such as oleic acid and its glyceride derivatives are useful in thepreparation of injectables, as are natural pharmaceutically-acceptableoils, such as olive oil or castor oil, especially in theirpolyoxyethylated versions. These oil solutions or suspensions may alsocontain a long-chain alcohol diluent or dispersant, such ascarboxymethyl cellulose or similar dispersing agents that are commonlyused in the formulation of pharmaceutically acceptable dosage formsincluding emulsions and suspensions. Other commonly used surfactants,such as Tweens, Spans and other emulsifying agents or bioavailabilityenhancers which are commonly used in the manufacture of pharmaceuticallyacceptable solid, liquid, or other dosage forms may also be used for thepurposes of formulation.

The compositions of this invention may be orally administered in anyorally acceptable dosage form including, but not limited to, capsules,tablets, aqueous suspensions or solutions. In the case of tablets fororal use, carriers commonly used include lactose and corn starch.Lubricating agents, such as magnesium stearate, are also typicallyadded. For oral administration in a capsule form, useful diluentsinclude lactose and dried cornstarch. When aqueous suspensions arerequired for oral use, the active ingredient is combined withemulsifying and suspending agents. If desired, certain sweetening,flavoring or coloring agents may also be added.

Alternatively, the compositions of this invention may be administered inthe form of suppositories for rectal administration. These can beprepared by mixing the agent with a suitable non-irritating excipientthat is solid at room temperature but liquid at rectal temperature andtherefore will melt in the rectum to release the drug. Such materialsinclude cocoa butter, beeswax and polyethylene glycols. Suchcompositions are prepared according to techniques well-known in the artof pharmaceutical formulation.

The compositions of this invention may be administered topically,especially when the target of treatment includes areas or organs readilyaccessible by topical application, including diseases of the eye, theskin, the joints, or the lower intestinal tract. Suitable topicalformulations are readily prepared for each of these areas or organs.Topical application for the lower intestinal tract can be effected in arectal suppository formulation (see above) or in a suitable enemaformulation. Topically-transdermal patches may also be used.

For topical applications, the compositions may be formulated in asuitable ointment containing the active component suspended or dissolvedin one or more carriers. Carriers for topical administration of thecompounds of this invention include, but are not limited to, mineraloil, liquid petrolatum, white petrolatum, propylene glycol,polyoxyethylene, polyoxypropylene compound, emulsifying wax and water.Alternatively, the compositions can be formulated in a suitable lotionor cream containing the active components suspended or dissolved in oneor more pharmaceutically acceptable carriers. Suitable carriers include,but are not limited to, mineral oil, sorbitan monostearate, polysorbate60, cetyl esters wax, cetearyl alcohol, 2-octyldodecanol, benzyl alcoholand water.

For ophthalmic use, the compositions may be formulated as micronizedsuspensions in isotonic, pH adjusted sterile saline, or, preferably, assolutions in isotonic, pH adjusted sterile saline, either with orwithout a preservative such as benzylalkonium chloride. Alternatively,for ophthalmic uses, the compositions may be formulated in an ointmentsuch as petrolatum.

The compositions of this invention may also be administered by nasalaerosol or inhalation. Such compositions are prepared according totechniques well-known in the art of pharmaceutical formulation and maybe prepared as solutions in saline, employing benzyl alcohol or othersuitable preservatives, absorption promoters to enhance bioavailability,fluorocarbons, and/or other conventional solubilizing or dispersingagents.

In one embodiment, the antibodies or therapeutic compounds of thisinvention may be incorporated into liposomes (“immunoliposomes” in thecase of antibodies), alone or together with another substance fortargeted delivery to a patient or an animal. Such other substances caninclude nucleic acids for the delivery of genes for gene therapy or forthe delivery of antisense RNA, RNAi or siRNA for activating NK cells orinhibiting mature dendritic cells, or toxins or drugs for the activationof NK cells (or inhibition of dendritic cells) through other means, orany other agent described herein that may be useful for the purposes ofthe present invention.

In another embodiment, the antibodies or other compounds of theinvention can be modified to improve its bioavailability, half life invivo, etc. For example, antibodies and other compounds can be pegylated,using any of the number of forms of polyethylene glycol and methods ofattachment known in the art (see, e.g., Lee et al. (2003) BioconjugChem. 14(3):546-53; Harris et al. (2003) Nat Rev Drug Discov.2(3):214-21; Deckert et al. (2000) Int J Cancer. 87(3):382-90).

Determining Dosage and Frequency of Administration

As described above, an important part of the present invention istesting anti-NKG2A antibodies in nonhuman primates to determine safe andeffective doses and frequencies of administration. Suitable startingadministration regimens can be determined by examining experience withother already developed therapeutic monoclonal antibodies. Severalmonoclonal antibodies have been shown to be efficient in clinicalsituations, such as Rituxan (Rituximab), Herceptin (Trastuzumab) Xolair(Omalizumab), Bexxar (Tositumomab), Campath (Alemtuzumab), Zevalin,Oncolym and similar administration regimens (i.e., formulations and/ordoses and/or administration protocols) may be used with the antibodiesof this invention. Schedules and dosages for administration can bedetermined in accordance with known methods for these products, forexample using the manufacturers' instructions. For example, a monoclonalantibody can be supplied at a concentration of 10 mg/mL in either 100 mg(10 mL) or 500 mg (50 mL) single-use vials. The product is formulatedfor IV administration in 9.0 mg/mL sodium chloride, 7.35 mg/mL sodiumcitrate dihydrate, 0.7 mg/mL polysorbate 80, and Sterile Water forInjection. The pH is adjusted to 6.5. An exemplary suitable dosage rangefor an antibody of the invention may be between about 10 mg/m2 and 500mg/m2. However, it will be appreciated that these schedules areexemplary and that optimal schedule and regimen can be adapted takinginto account the affinity and anti-NKG2A activity of the antibody andthe tolerability of the antibodies that must be determined in clinicaltrials. Quantities and schedule of injection of antibodies to NKG2Asthat saturate cells for 24 hours, 48 hours, 72 hours or a week or amonth will be determined considering the affinity of the antibody andits pharmacokinetic parameters.

However, it will be appreciated that these schedules are exemplary andthat optimal schedule and regimen can be adapted taking into account theaffinity and anti-NKG2A activity of the antibody and the tolerability ofthe antibodies that must be determined in clinical or preclinicaltrials. Quantities and schedule of injection of antibodies to NKG2Asthat saturate cells for 24 hours, 48 hours 72 hours or a week or a monthwill be determined considering the affinity of the antibody and the itspharmacokinetic parameters.

The dose administered to a patient or nonhuman primate in the presentmethods should be sufficient to effect a beneficial response in thesubject over time. The dose will be determined by the efficacy of theparticular modulators employed and the condition of the subject, as wellas the body weight or surface area of the area to be treated. The sizeof the dose also will be determined by the existence, nature, and extentof any adverse side-effects that may accompany administration in aparticular subject. In determining the effective amount of the compoundto be administered in a particular patient, a physician may evaluatecirculating plasma levels of the compound, compound toxicities, and theproduction of anti-compound antibodies. In general, the dose equivalentof a compound is from about 1 ng/kg to 10 mg/kg for a typical subject.Administration can be accomplished via single or divided doses.

The antibodies of the invention that bind both human and non-humanprimate NKG2A receptors can be advantageously used in determining dosageand frequency of administration. The selection of an optimal therapeuticwindow for therapy with an anti-NKG2A antibody can be carried out basedon administration of the antibody to a non-human primate. While NK cellactivation in the short term (24 hour co-culture) has been suggested toavoid bone marrow cell (BMC) toxicity, it has been shown that longer (48hour co-culture of bone marrow cells with activated NK cells) adverselyaffects hematopoietic reconstitution (Koh et al. (2002) Biol. BloodMarrow Transplant. 8:17-25). However, it would be valuable to employadministration regimens that permit exposure of NK cells in anindividual to an NK cell activation anti-NKG2A antibody for a longerperiod, e.g. longer than 24 hours or even 48 hours. While not wishing tobe bound by theory such a regimen where an anti-NKG2A antibody ispresent for greater than 24 hours or 48 hours would enable theanti-NKG2A antibody to come into contact with and activate a sufficientnumber of NK cells in the individual for a therapeutic effect againsttarget (e.g. cancer, infected, inflammatory) cells. The inventorstherefore provide a method of treating an individual with an anti-NKG2Aantibody comprising exposing said individual to an anti-NKG2A antibodyfor a period for a period greater than 24 hours, more preferably 48hours. Most preferably the invention comprises administering to saidindividual an anti-NKG2A antibody having a plasma half-life greater than24 hours, or 48 hours, or more preferably of at least 5, 6, 7, 10, 14 or20 days. Most preferably the invention comprises administering to saidindividual an anti-NKG2A antibody comprising an Fc portion, preferablyan Fc portion of the G2 or G4 type. As further discussed herein, anysuitable antibody that blocks NKG2A function can be used, for example anantibody having the binding specificity of Z199 or Z270. In preferredembodiments the antibody is administered in a second or further dose andthe antibody will be a chimeric, CDR grafted, human or humanizedantibody.

The present invention provides a method of identifying a suitableadministration regimen for a therapeutic antibody directed against humanNKG2A, the method comprising administering the antibody to a nonhumanprimate using an administration regimen, preferably a series of regimensin which the dose or frequency of the antibody is varied, anddetermining the activity of NKG2A-expressing cells in the non-humanprimate and the effect of therapy on bone marrow cells (BMC) and/orhematopoietic cells, particularly myeloid cell reconstitution, of theprimate for the particular administration regimen(s). Preferably themethod further comprises assessing myeloid reconstitution followinganti-NKG2A antibody administration, generally involving determining thenumber of days required for myeloid reconstitution to normalize, e.g. tolevels approaching that observed prior to anti-NKG2A therapy or to apredetermined minimum level. It is then possible to select or identifyan administration regimen that allows myeloid reconstitution tonormalize.

The method can further comprise determining the activity ofNKG2A-expressing cells in the non-human primate and/or identifying orselecting an administration regimen that leads to a detectablemodulation in the activity of NKG2A-expressing cells.

Said administration regimen(s) can be expressed for example in terms ofperiod of exposure of an individual to an anti-NKG2A antibody thatactivates an NK cell, and frequency of antibody administration. Based onsuch parameters, administration frequency and dosage can be adapteddepending on the particular antibody used, e.g. taking account of theantibody's plasma half-life, affinity, bioavailability (or time to peakserum concentration), etc.

A determination that a regimen permits partial or complete recovery ornormalization of myeloid reconstitution by the primate and leads to adetectable modulation in the activity of NKG2A-expressing cellsindicates that the administration regimen is suitable for use in humans.

The catabolic rates of the endogenous human immunoglobulins have beenwell characterized. The half-life of IgG varies according to isotype, upto 3 weeks for IgG1, IgG2, and IgG4 and approximately 1 week for IgG3.Unless pharmacokinetics are altered by antigen binding orimmunogenicity, intact human IgG monoclonal antibodies will exhibitpharmacokinetics comparable to endogenous IgG. As discussed previously,the extraordinarily long half-life of the human IgG1, IgG2, and IgG4isotypes is due to catabolic protection by FcRn. FcRn is expressed onhepatocytes, endothelial cells, and phagocytic cells of thereticuloendothelial system (RES). When IgG undergoes endocytosis, thelow pH of the endosome promotes binding of the IgG Fc domain to FcRn,which recycles IgG to the cell surface and salvages IgG from lysosomaldegradation. The short half life of IgG3 compared to the other IgGisotypes is due to a single amino acid difference (an arginine insteadof a histidine at position 435) in the FcRn binding domain.

The elimination of intact murine IgG1 and IgG2 antibodies is much fasterthan the corresponding human isotypes. Half-lives for murine antibodiesare in the range of 12 to 48 hours in humans. The short half-life ofmurine antibodies in humans is due to low-affinity binding of the murineFc domain to human FcRn. Human FcRn binds to human, rabbit, and guineapig IgG, but not significantly to rat, bovine, sheep, or mouse IgG;mouse FcRn binds to IgG from all of these species. Antibody fragments,including F(a′)₂, Fab, and scFV, lack the Fc domain and do not bind toFcRn. Therefore, the half-lives of these fragments are substantiallyshorter than intact IgG, with half-life determined predominantly bytheir molecular weights. Lower molecular weight Fab and scFv fragmentsare subject to renal clearance, which accelerates elimination. Reportedhalf-lives have ranged from 11 to 27 h for F(ab′)2 fragments and 0.5 to21 h for Fab fragments. The half-life of monovalent and multivalent scFvconstructs may range from minutes to several hours.

Antigen binding can significantly affect the pharmacokinetics ofantibodies. If the antibody binds to an internalized cell membraneantigen or an immune complex formed with a secreted antigen isefficiently eliminated from circulation, the antigen may act as a “sink”for antibody clearance. An antigen sink will produce dose-dependentpharmacokinetics. If the dose level is insufficient to saturate theantigen pool, antigen-mediated clearance will predominate and theantibody half-life will be shorter than the half-life of endogenous IgG;at dose levels that saturate the antigen, RES-mediated clearance willpredominate and half-life will be similar to endogenous IgG.

A preferred embodiment of the present invention describes a dosingregimen wherein anti-NKG2A antibody is administered in a firstadministration. The first dose of anti-NKG2A antibody activates NK cellsand may indirectly by activating NK cells inhibit myeloid cellreconstitution in the individual. The second dose of anti-NKG2A antibodyis administered to coincide with the pharmacodynamic profile of myeloidcell reconstitution recovery, e.g. to be administered at a time when anindividual's rate of myeloid cell reconstitution is expected to have atleast partially recovered. Thus, by using an anti-NKG2A antibody whichcross-reacts with the receptor in humans and non-human primates, theinventors provide a method in which NK cells are brought into contactwith an anti-NKG2A antibody for a period greater than 24 hours duringwhich myeloid reconstitution has been reported to not be affected.

In preferred embodiments, the second dose of anti-NKG2A antibody will beadministered at least 6, 7, 8, 9 or 10 days following the initial dose,and preferably at least 14, 15, 16, or 20 days following the initialdose. Most preferably the second dose of anti-NKG2A antibody will beadministered at least 2, 3, 4, 5, 6, 7, 8, 9 or 10 days or at least 14,15, 16, or 20 days following the time (day) at which anti-NKG2A antibodyplasma concentration in a subject is estimated to reach half of theinitial (at administration) concentration, preferably at least 6-10 daysor at least 15-20 days following the duration of at least one plasmahalf-life of the anti-NKG2A antibody. Alternatively, the method can beexpressed in terms of peak serum concentration of the anti-NKG2Aantibody, where the second dose of anti-NKG2A antibody will beadministered at least 2, 3, 4, 5, 6, 7, 8, 9 or 10 days or at least 14,15, 16, or 20 days following the time (day) at which anti-NKG2A antibodyplasma concentration in a subject is estimated to reach half of the peakserum concentration in the individual.

In a further embodiment, the second dose of anti-NKG2A antibody will beadministered at least 2, 3, 4, 5, 6, 7, 8, 9 or 10 days or at least 14,15, 16, or 20 days following the time (day) at which anti-NKG2A antibodyplasma concentration in a subject is estimated to reach a non-detectableconcentration, preferably at least 2, 3, 4, 5, 6, 7, 8, 9 or 10 days orat least 14, 15, 16, or 20 days following the duration of at least 2, 3,4 or more plasma half-lives of the anti-NKG2A antibody.

In a preferred embodiment, an administration regimen is described for anantibody comprising an Fc region of the G2b or preferably G4 subtype(IgG2b or IgG4 respectively). Preferably said antibody has a plasmahalf-life of about 5, 6, 7, 8, 9, 10, 12, 15, 18, 20, or 21 days, orpreferably of about 10 to 15 days, 15-21 days. Preferably the antibodycomprises an Fc region substantially free of binding to Fc receptors onNK cells (CD16). Said antibody is preferably administered in a firstdose, and a second and/or subsequent dose, wherein the second and/orsubsequent dose is administered at least 6, 7, 8, 9, 10, 14, 15, 16, or20 days after the antibody is estimated to reach half its initialconcentration. Said second and/or subsequent dose can also be expressedin absolute number of days following administration, e.g. preferably atleast 6, 7, 8, 9 or 10 days following the initial dose, and preferablyat least 14, 15, 16, 20, 21, 24, 28, 30 or 35 days following the firstadministration. Said antibody may be an antibody comprising a naturallyoccurring Fc portion, preferably a naturally occurring human Fc portion,or more preferably may contain modifications such as one or more aminoacid substitutions that increase the plasma half-life of the antibodyand/or that modify binding to Fc receptors, for example increase bindingto Fcn receptors to increase plasma half-life or decrease binding toFcgammaIIIa to decrease unwanted toxicity (ADCC) towards the NK cell.Such modifications can be carried out according to methods well known inthe art, several of which modifications are further described herein.

In yet another preferred embodiment, an administration regimen isdescribed for an antibody fragment, preferably a F(ab′)2 fragmentmodified, for example with polyethylene glycol as described herein, tohave a plasma half-life of about 5, 6, 7, 8, 9, 10, 12, 15, 18, 20, or21 days. Said antibody is preferably administered in a first dose, and asecond and/or subsequent dose, wherein the second and/or subsequent doseis administered at least 6, 7, 8, 9, 10, 14, 15, 16, or 20 days afterthe antibody is estimated to reach half its initial concentration. Saidsecond and/or subsequent dose can also be expressed in absolute numberof days following administration, e.g. preferably at least 6, 7, 8, 9 or10 days following the initial dose, and preferably at least 14, 15, 16,20, 21, 24, 28, 30 or 35 days following the first administration.

Pharmaceutical Combinations

According to another important embodiment of the present invention, theanti-NKG2A antibodies and/or other compounds may be formulated togetherwith one or more additional therapeutic agents, including agentsnormally utilized for the particular therapeutic purpose for which theantibody or compound is being administered. The additional therapeuticagent will generally be administered at a dose typically used for thatagent in a monotherapy for the particular disease or condition beingtreated. Such therapeutic agents include, but are not limited to,therapeutic agents used in the treatment of cancers (“anticancercompounds”; including chemotherapeutic compounds, hormones, angiogenesisinhibitors, apoptotic agents, etc.); therapeutic agents used to treatinfectious disease (including antiviral compounds); therapeutic agentsused in other immunotherapies, such as the treatment of autoimmunedisease, inflammatory disorders, and transplant rejection; cytokines;immunomodulatory agents; adjunct compounds; or other antibodies andfragments of other antibodies against both activating and inhibitory NKcell receptors. Unless otherwise specifically stated, the combinationcompositions set forth below can comprise either an activating antibody,an inhibitory antibody or a cytotoxin-antibody conjugate of thisinvention.

Therapeutic agents for the treatment of cancer include chemotherapeuticagents (including agents that interfere with DNA replication, mitosisand chromosomal segregation, and agents that disrupt the synthesis andfidelity of polynucleotide precursors), hormonal therapy agents,anti-angiogenic agents, and agents that induce apoptosis.

Chemotherapeutic agents contemplated as exemplary include, but are notlimited to, alkylating agents, antimetabolites, cytotoxic antibiotics,vinca alkaloids, for example adriamycin, dactinomycin, mitomycin,carminomycin, daunomycin, doxorubicin, tamoxifen, taxol, taxotere,vincristine, vinblastine, vinorelbine, etoposide (VP-16), 5-fluorouracil(5FU), cytosine arabinoside, cyclophosphamide, thiotepa, methotrexate,camptothecin, actinomycin-D, mitomycin C, cisplatin (CDDP), aminopterin,combretastatin(s) and derivatives and prodrugs thereof.

Hormonal agents include, but are not limited to, for example LHRHagonists such as leuprorelin, goserelin, triptorelin, and buserelin;anti-estrogens such as tamoxifen and toremifene; anti-androgens such asflutamide, nilutamide, cyproterone and bicalutamide; aromataseinhibitors such as anastrozole, exemestane, letrozole and fadrozole; andprogestagens such as medroxy, chlormadinone and megestrol.

A number of exemplary chemotherapeutic agents for combined therapy arelisted in Table C of U.S. Pat. No. 6,524,583, the disclosure of whichagents and indications are specifically incorporated herein byreference. Each of the agents listed are exemplary and not limiting. Theskilled artisan is directed to “Remington's Pharmaceutical Sciences”15th Edition, chapter 33, in particular pages 624-652. Variation indosage will likely occur depending on the condition being treated. Thephysician administering treatment will be able to determine theappropriate dose for the individual subject.

Examples of anti-angiogenic agents include neutralizing antibodies,antisense RNA, siRNA, RNAi, RNA aptamers and ribozymes each directedagainst VEGF or VEGF receptors (U.S. Pat. No. 6,524,583, the disclosureof which is incorporated herein by reference).

Variants of VEGF with antagonistic properties may also be employed, asdescribed in WO 98/16551, specifically incorporated herein by reference.Further exemplary anti-angiogenic agents that are useful in connectionwith combined therapy are listed in Table D of U.S. Pat. No. 6,524,583,the disclosure of which agents and indications are specificallyincorporated herein by reference.

Exemplary apoptotic agents include, but are not limited to, bcr-abl,bcl-2 (distinct from bcl-1, cyclin D1; GenBank accession numbers M14745,X06487; U.S. Pat. Nos. 5,650,491 and 5,539,094; each incorporated hereinby reference) and family members including Bcl-x1, Mcl-1, Bak, A1, andA20. Overexpression of bcl-2 was first discovered in T cell lymphomas.The oncogene bcl-2 functions by binding and inactivating Bax, a proteinin the apoptotic pathway. Inhibition of bcl-2 function preventsinactivation of Bax, and allows the apoptotic pathway to proceed.Inhibition of this class of oncogenes, e.g., using antisense nucleotidesequences, RNAi, siRNA or small molecule chemical compounds, iscontemplated for use in the present invention to give enhancement ofapoptosis (U.S. Pat. Nos. 5,650,491; 5,539,094; and 5,583,034; eachincorporated herein by reference).

Useful anti-viral agents that can be used in combination with themolecules of the invention include, but are not limited to, proteaseinhibitors, nucleoside reverse transcriptase inhibitors, non-nucleosidereverse transcriptase inhibitors and nucleoside analogs. Examples ofantiviral agents include but are not limited to zidovudine, acyclovir,gangcyclovir, vidarabine, idoxuridine, trifluridine, and ribavirin, aswell as foscarnet, amantadine, rimantadine, saquinavir, indinavir,amprenavir, lopinavir, ritonavir, the alpha-interferons, adefovir,clevadine, entecavir, and pleconaril.

For autoimmune or inflammatory disorders, any other compound known to beeffective for one or more types of autoimmune or inflammatory disorders,or any symptom or feature of autoimmune or inflammatory disorders,including inter alia, immunosuppressants, e.g., azathioprine (e.g.,Imuran), chlorambucil (e.g., Leukeran), cyclophosphamide (e.g.,Cytoxan), cyclosporine (e.g., Sandimmune, Neoral), methotrexate (e.g.,Rheumatrex), corticosteroids, prednisone (e.g., Deltasone, Meticorten),Etanercept (e.g., Enbrel), infliximab (e.g., Remicade), inhibitors ofTNF, FK-506, rapamycin, mycophenolate mofetil, leflunomide,anti-lymphocyte globulin, deoxyspergualin or OKT.

Preferred examples of immunomodulatory compounds include cytokines.Other examples include compounds that have an effect, preferably aneffect of activation or potentiation of NK cell activity, or of inducingor supporting the proliferation of NK cells. Examples ofimmunomodulating compounds include but are not limited to ligands of NODand PKR receptors, agonists of TLRs (Toll-like receptors), such asagonists of TLR3 (dsRNA, poly I:C and poly A:U), TLR4 (ANA380,isatoribine, LPS and mimetics such as MPL), TLR7 (oligonucleotides,ssRNA), TLR9 (oligonucleotides such as CpGs), a number of examples ofwhich are described in Akira and Takeda ((2004) Nature Reviews 4: 499),and antibodies that block inhibitory receptors on NK cells (for examplethat inhibit KIR2DL1 and KIR2DL2/3 activity) or act as agonists at NKcell activatory receptors (for example antibodies that crosslink NCRreceptors NKp30, NKp44 or NKp46). Various cytokines may be employed incombined approaches according to the invention. Examples of cytokinesuseful in the combinations contemplated by this invention includeIL-1alpha IL-1beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9,IL-10, IL-11, IL-12, IL-13, IL-15, IL-21, TGF-beta, GM-CSF, M-CSF,G-CSF, TNF-alpha, TNF-beta, LAF, TCGF, BCGF, TRF, BAF, BDG, MP, LIF,OSM, TMF, PDGF, IFN-alpha, IFN-beta, IFN-gamma. Cytokines used in thecombination treatment or compositions of this invention are administeredaccording to standard regimens, consistent with clinical indicationssuch as the condition of the patient and relative toxicity of thecytokine.

Adjunct compounds may include by way of example anti-emetics such asserotonin antagonists and therapies such as phenothiazines, substitutedbenzamides, antihistamines, butyrophenones, corticosteroids,benzodiazepines and cannabinoids; bisphosphonates such as zoledronicacid and pamidronic acid; and hematopoietic growth factors such aserythropoietin and G-CSF, for example filgrastim, lenograstim anddarbepoietin.

Other therapeutic agents that can be formulated with the activatinganti-NKG2A antibodies of this invention include other compounds that canactivate NK cells. For example, compounds that stimulate NCRs, e.g.NKp30, NKp44, and NKp46, can be used (see, e.g., PCT WO 01/36630, Vitaleet al. (1998) J. Exp. Med. 187:2065-2072, Sivori et al. (1997) J. Exp.Med. 186:1129-1136; Pessino et al. (1998) J. Exp Med. 188:953-960; theentire disclosures of which are herein incorporated by reference), ascan inhibitors of the KIR inhibitory receptors (see, e.g., Yawata et al.(2002) Crit Rev Immunol 22:463-82; Martin et al. (2000) Immunogenetics.51:268-80; Lanier (1998) Annu Rev Immunol. 16:359-93; the entiredisclosures of which are herein incorporated by reference). Preferably,an activator, e.g. natural ligand or activating antibody, of NKp30 isused. In one embodiment, an inhibitor of TGF-beta 1 is used, as TGF-beta1 can downregulate NKp30 (see, e.g., Castriconi et al. (2004) C.R.Biologies 327:533-537, the entire disclosure of which is hereinincorporated in its entirety).

Therapeutic compounds that can be formulated with the inhibitoryanti-NKG2A antibodies of this invention are compounds that can inhibitNK cells. Such compounds include inhibitors of NCRs, e.g. NKp30, NKp44,and NKp46, inhibitors of activating NKG2 receptors (e.g., NKG2C),activators of inhibitory KIR receptors, or activators of an inhibitoryLy49 receptor.

The activating antibodies of this invention may also be formulatedtogether with an antigen to which tolerance is desired. It is believedthat the enhanced killing of dendritic cells caused by the activatingantibodies of this invention will cause tolerization of antigenspresented to the immune system at that time. Such compositions areuseful in treating autoimmune disease, as well as allergies. Examples ofantigens that may be formulated with the activating antibodies of thisinvention include myelin basic protein, ragweed and other pollen andplant allergens, allergens responsible for pet allergies, allergensresponsible for food allergies (such as peanut and other nut allergens,dairy product allergens, sesame and other seed allergens) or insectallergens.

The interrelationship of dosages for animals and humans (based onmilligrams per meter squared of body surface) is described in Freireichet al., (1966) Cancer Chemother Rep 50: 219. Body surface area may beapproximately determined from height and weight of the patient. See,e.g., Scientific Tables, Geigy Pharmaceuticals, Ardley, N.Y., 1970, 537.An effective amount of a compound of this invention can range from about0.001 mg/kg to about 1000 mg/kg, more preferably 0.01 mg/kg to about 100mg/kg, more preferably 0.1 mg/kg to about 10 mg/kg; or any range inwhich the low end of the range is any amount between 0.001 mg/kg and 900mg/kg and the upper end of the range is any amount between 0.1 mg/kg and1000 mg/kg (e.g., 0.005 mg/kg and 200 mg/kg, 0.5 mg/kg and 20 mg/kg).Effective doses will also vary, as recognized by those skilled in theart, depending on the diseases treated, route of administration,excipient usage, and the possibility of co-usage with other therapeutictreatments such as use of other agents.

For pharmaceutical compositions that comprise additional therapeuticagents, an effective amount of the additional therapeutic agent isbetween about 20% and 100% of the dosage normally utilized in amonotherapy regime using just that additional agent. Preferably, aneffective amount is between about 70% and 100% of the normalmonotherapeutic dose. The normal monotherapeutic dosages of theseadditional therapeutic agents are well known in the art. See, e.g.,Wells et al., eds., Pharmacotherapy Handbook, 2nd supp. Edition,Appleton and Lange, Stamford, Conn. (2000); PDR Pharmacopoeia, TarasconPocket Pharmacopoeia 2000, Deluxe Edition, Tarascon Publishing, LomaLinda, Calif. (2000), each of which are entirely incorporated herein byreference.

It is expected that some of the additional therapeutic agents listedabove will act synergistically with the compounds of this invention.When this occurs, its will allow the effective dosage of the additionaltherapeutic agent and/or the compound of this invention to be reducedfrom that required in a monotherapy. This has the advantage ofminimizing toxic side effects of either the additional therapeutic agentof a compound of this invention, synergistic improvements in efficacy,improved ease of administration or use and/or reduced overall expense ofcompound preparation or formulation.

It will be recognized by those of skill in the art that certaintherapeutic agents set forth above fall into two or more of thecategories disclosed above. For the purpose of this invention, suchtherapeutic agents are to be considered members of each of thosecategories of therapeutics and the characterization of any therapeuticagent as being in a certain specified category does not preclude it fromalso being considered to be within another specified category.

In yet another embodiment, the invention provides a composition ofmatter comprising an antibody of this invention and a second therapeuticagent or an allergen, selected from any of the agents or allergens setforth above, wherein the antibody and the second agent are in separatedosage forms, but associated with one another. The term “associated withone another” as used herein means that the separate dosage forms arepackaged together or otherwise attached to one another such that it isreadily apparent that the separate dosage forms are intended to be soldand administered as part of the same regimen. The agent and the antibodyare preferably packaged together in a blister pack or othermulti-chamber package, or as connected, separately sealed containers(such as foil pouches or the like) that can be separated by the user(e.g., by tearing on score lines between the two containers).

In still another embodiment, the invention provides a kit comprising inseparate vessels, a) an antibody of this invention; and b) a secondtherapeutic agent or an allergen. Again, any of the therapeutic agentsor allergens set forth above may be present in such a kit.

Therapeutic Use of Anti-NKG2A Antibodies and Compositions

The activating antibodies of the present invention render NK cellscapable of lysing target cells bearing HLA-E or Qa1^(b) on their cellsurfaces when the NK cell comes into contact with the target cell. Thus,according to one embodiment, the invention provides a method ofreconstituting NK cell-mediated lysis of a target cell in a populationcomprising a NK cell and said target cell, wherein said NK cell ischaracterized by NKG2A on its surface, and said target cell ischaracterized by the presence of HLA-E or Qa1^(b) on its surface, saidmethod comprising the step of contacting said NK cell with anabove-described activating monoclonal antibody or a fragment thereof.

This activity is particularly useful in the treatment of conditions anddisorders characterized by deleterious cells expressing HLA-E or Qa1^(b)on their cell surface. One such cell type is a dendritic cell,preferably a mature dendritic cell. Thus, the invention provides amethod of treating an autoimmune or inflammatory disorder or any otherdisorder caused at least in part by an excess of dendritic cells, orhyperactive dendritic cell activity. The method of treating suchdisorders comprises the step of administering to a patient anon-cytotoxic composition of the present invention that comprises anactivating antibody.

Exemplary autoimmune disorders treatable using the present methodsinclude, inter alia, hemolytic anemia, pernicious anemia, polyarteritisnodosa, systemic lupus erythematosus, Wegener's granulomatosis,autoimmune hepatitis, Behçet's disease, Crohn's disease, primary bilarycirrhosis, scleroderma, ulcerative colitis, Sjögren's syndrome, Type 1diabetes mellitus, uveitis, Graves' disease, Alzheimer's disease,thyroiditis, myocarditis, rheumatic fever, ankylosing spondylitis,rheumatoid arthritis, glomerulonephritis, sarcoidosis, dermatomyositis,myasthenia gravis, polymyositis, Guillain-Barré syndrome, multiplesclerosis, alopecia areata, pemphigus/pemphigoid, Bullous pemphigoid,Hashimoto's thyroiditis, psoriasis, and vitiligo.

Examples of inflammatory disorders that can be treated by these methodsinclude, but are not limited to, adrenalitis, alveolitis,angiocholecystitis, appendicitis, balanitis, blepharitis, bronchitis,bursitis, carditis, cellulitis, cervicitis, cholecystitis, chorditis,cochlitis, colitis, conjunctivitis, cystitis, dermatitis,diverticulitis, encephalitis, endocarditis, esophagitis, eustachitis,fibrositis, folliculitis, gastritis, gastroenteritis, gingivitis,glossitis, hepatosplenitis, keratitis, labyrinthitis, laryngitis,lymphangitis, mastitis, media otitis, meningitis, metritis, mucitis,myocarditis, myosititis, myringitis, nephritis, neuritis, orchitis,osteochondritis, otitis, pericarditis, peritendonitis, peritonitis,pharyngitis, phlebitis, poliomyelitis, prostatitis, pulpitis, retinitis,rhinitis, salpingitis, scleritis, selerochoroiditis, scrotitis,sinusitis, spondylitis, steatitis, stomatitis, synovitis, syringitis,tendonitis, tonsillitis, urethritis, and vaginitis.

It has also been shown that alloreactive NK cell killing of dendriticcells improved engraftment of hematopoietic cells in a bone marrowtransplant (L. Ruggeri et al., Science, 2002, 295:2097-2100). Thus, inanother embodiment, the invention provides a method of improving theengraftment of hematopoietic cells in a patient comprising the step ofadministering to said patient a composition of this invention comprisingan activating antibody. Improvement in grafting is manifested by any oneof reduced incidence or severity of graft versus host disease, prolongedsurvival of the graft, or a reduction in or elimination of the symptomsof the disease being treated by the graft (e.g., a hematopoieticcancer). This method is preferably used in the treatment of leukemia.

Cancer cells have also been shown to evade killing through the presenceof HLA-E on their surface. HLA-E has been detected on surgically removedglioblastoma specimens, in glioma cell lines and glioblastoma cellcultures (J. Wischhusen et al., J Neuropathol Exp Neurol. 2005;64(6):523-8); and in leukemia-derived cell lines, melanomas,melanoma-derived cell lines and cervical tumors (R Marin et al.,Immunogenetics. 2003; 54(11):767-75). Thus, in another embodiment, theinvention provides a method of treating a patient suffering from cancer,wherein said cancer is characterized by a cell expressing HLA-E, saidmethod comprising the step of administering to said patient acomposition of the present invention comprising an activating antibody.

Examples of cancers that may be treated according to this methodinclude, but are not limited to, carcinoma, including that of thebladder, breast, colon, kidney, liver, lung, ovary, prostate, pancreas,stomach, cervix, thyroid and skin, including squamous cell carcinoma;hematopoietic tumors of lymphoid lineage, including leukemia, acutelymphocytic leukemia, acute lymphoblastic leukemia, B-cell lymphoma,T-cell lymphoma, Hodgkins lymphoma, non-Hodgkins lymphoma, hairy celllymphoma and Burketts lymphoma; hematopoietic tumors of myeloid lineage,including acute and chronic myelogenous leukemias and promyelocyticleukemia; tumors of mesenchymal origin, including fibrosarcoma andrhabdomyoscarcoma; other tumors, including melanoma, seminoma,teratocarcinoma, neuroblastoma and glioma; tumors of the central andperipheral nervous system, including astrocytoma, neuroblastoma, glioma,and schwannomas; tumors of mesenchymal origin, including fibrosarcoma,rhabdomyoscaroma, and osteosarcoma; and other tumors, includingmelanoma, xeroderma pigmentosum, keratoacanthoma, seminoma, thyroidfollicular cancer and teratocarcinoma.

Preferred cancers that can be treated according to the invention includegliomas, glioblastomas, leukemias, melanomas, and cervical tumors.

Virally infected cells also use HLA-E expression as a mechanism ofavoiding NK cell killing. HLA-E expression has been associated withhepatitis C virus infected cells (J. Mattermann et al, American Journalof Pathology. 2005; 166:443-453); and cytomegalovirus infected cells (C.Cerboni et al., Eur J Immunol. 2001; 31(10):2926-35). Thus, in anotherembodiment, the invention provides a method of treating a patientsuffering from a viral infection, wherein said viral infection ischaracterized by a virally-infected cell expressing HLA-E, said methodcomprising the step of administering to said patient a composition ofthe present invention comprising an activating antibody.

Examples of viral infections that may be treated by this method include,but are not limited to, infections caused by viruses of the familyRetroviridae (e.g., human immunodeficiency viruses, such as HIV-1 (alsoreferred to as HTLV-III, LAV or HTLV-III/LAV, or HIV-III; and otherisolates, such as HIV-LP)); Picornaviridae (e.g., polio viruses,hepatitis A virus, enteroviruses, human Coxsackie viruses, rhinoviruses,echoviruses); Calciviridae (e.g., strains that cause gastroenteritis);Togaviridae (e.g., equine encephalitis viruses, rubella viruses);Flaviviridae (e.g., dengue viruses, encephalitis viruses, yellow feverviruses); Coronaviridae (e.g., coronaviruses); Rhabdoviridae (e.g.,vesicular stomatitis viruses, rabies viruses); Filoviridae (e.g., ebolaviruses); Paramyxoviridae (e.g., parainfluenza viruses, mumps virus,measles virus, respiratory syncytial virus); Orthomyxoviridae (e.g.,influenza viruses) or avian influenza viruses (e.g. H5N1 or relatedviruses); Bungaviridae (e.g., Hantaan viruses, bunga viruses,phleboviruses and Nairo viruses); Arenaviridae (hemorrhagic feverviruses); Reoviridae (e.g., reoviruses, orbiviruses and rotaviruses);Birnaviridae; Hepadnaviridae (Hepatitis B virus); Parvoviridae(parvoviruses); Papovaviridae (papillomaviruses, polyoma viruses);Adenoviridae (most adenoviruses); Herpesviridae (herpes simplex virus(HSV) 1 and 2, varicella zoster virus, cytomegalovirus (CMV));Poxviridae (variola viruses, vaccinia viruses, pox viruses);Iridoviridae (e.g., African swine fever virus); and unclassified viruses(e.g., the etiological agents of spongiform encephalopathies, the agentof delta hepatitis (thought to be a defective satellite of hepatitis Bvirus), the agents of non-A, non-B hepatitis (class 1=internallytransmitted; class 2=parenterally transmitted (i.e., Hepatitis C);Norwalk and related viruses, and astroviruses).

Most preferably, the viral infection to be treated is selected from ahepatitis C virus infection or a cytomegalovirus infection.

The activating antibodies of this invention can also be used to inducetolerance to an antigen. Thus, according to another embodiment, theinvention provides a method of inducing tolerance to an antigen in apatient comprising the steps of administering to said patient acomposition of this invention comprising an activating antibody; andadministering to said patient an antigen to which tolerance is desired.The method is preferably used to treat an allergy, wherein the antigenis an allergen. The choice of antigen can be made from those set forthabove for combination compositions comprising an activating antibody ofthis invention and an antigen.

Compositions comprising the inhibitory antibodies of this invention orcytotoxin-antibody conjugates are useful for killing NK cells, reducingthe activity of NK cells, reducing proliferation of NK cells, preventingthe lysis of cells susceptible to NK cell lysis, or reducing the numberof NK cells in a population. According to one embodiment, the inventionprovides a method of reducing the activity of NK cells, reducingproliferation of NK cells, preventing the lysis of cells susceptible toNK cell lysis, or reducing the number of NK cells in a populationcomprising the step of contacting a NK cell with a composition of thisinvention comprising an inhibitory antibody or a cytotoxin-antibodyconjugate. These methods are particularly useful in diseasescharacterized by NK hyperactivity and/or hyperproliferation.

For example, co-owned PCT publication WO2005/105849 generally describesthe use of antibodies against various NK cell receptors for thetreatment of NK-Type LDGL. PCT publication WO 2005/115517 discloses thatNK cell hyperactivity is associated with the presence, progression,stage and/or aggressiveness of pancreatic islet autoimmunity and thusplays a role in Type-I diabetes. Thus, according to one embodiment, theinvention provides a method of treating a patient suffering from acondition characterized by NK cell hyperactivity or NK cellhyperproliferation comprising the step of administering to said patienta composition according to this invention comprising an inhibitoryantibody or a cytotoxin-antibody conjugate. In a preferred embodiment,the condition is selected from NK-Type LDGL or Type I diabetes.

Any of the therapeutic methods described above may comprise theadditional step of administering to the patient a second therapeuticagent suitable for the condition being treated. Examples of the types ofsecond therapeutic agents that may be administered to the patientinclude a cytokine, a cytokine inhibitor, a hematopoietic growth factor,insulin, an anti-inflammatory agent, an immunosuppressant, an anticancercompound (such as a chemotherapeutic compound, an anti-angiogeniccompound, an apoptosis-promoting compound, a hormonal agent, a compoundthat interferes with DNA replication, mitosis and/or chromosomalsegregation, or an agent that disrupts the synthesis and fidelity ofpolynucleotide precursors), an adjunct compound (such as a pain relieveror an antiemetic), a compound that agonizes an activating NK cellreceptor (such as NKp30, NKp44, and NKp46), an antagonist of aninhibitory NK cell receptor (such as an inhibitory KIR receptor), anantagonist of TGF-beta 1, a compound capable of stimulating aninhibitory NK cell receptor (such as natural ligands, antibodies orsmall molecules that can stimulate the activity of CD94/NKG2A receptors,or an inhibitory KIR receptor such as KIR2DL1, KIR2DL2, KIR2DL3,KIR3DL1, and KIR3DL2), or an inhibitor of an activating NK cell receptor(such as NKp30, NKp44, or NKp46).

Specific examples of the above-described classes of compounds are setforth in the section on pharmaceutical combinations and any of suchspecific compounds, as well as other members of any of these classes oftherapeutic agents may be administered to a patient in the methods ofthis invention. The choice of therapeutic agent to use is easily made bythose of skill in the medical arts and is dependent upon the nature ofthe condition being treated or prevented, the severity of the condition,the general overall health of the patient being treated, and thejudgment of the treating physician.

The second therapeutic agent may be administered simultaneously with,prior to, or following the anti-NKG2A composition of this invention.When administered simultaneously, the second therapeutic agent may beadministered as either a separately formulated composition (i.e., as amultiple dosage form), or as part of the antibody-containingcomposition.

In some embodiments, prior to the administration of a NKG2A antibodycomposition of this invention, the expression of NKG2A, and possiblyother proteins, on NK cells will be assessed, and/or the activity ornumber of dendritic cells (preferably mature dendritic cells) and/or thepresence of a NKG2A ligand (e.g., HLA-E or Qa1^(b)) on other cells, willbe measured. This can be accomplished by obtaining a sample of NK ordendritic cells from the patient, and, for NK cells, testing e.g., usingimmunoassays, to determine the relative prominence of markers such asKIR receptors, other NKG2A receptors, or NCRs (e.g., NKp30, NKp44,NKp46), on the cells. Other methods can also be used to detectexpression of these proteins, such as RNA-based methods, e.g., RT-PCR orNorthern blotting. The detection of NK cells expressing NKG2A in thepatient indicates that the present methods are well suited for use intreating the patient.

The treatment may involve multiple rounds of antibody. For example,following an initial round of administration, the level and/or activityof NKG2A-expressing NK cells, and/or dendritic cells or other cellsexpressing NKG2A or HLA-E, or Qa1^(b) on their surface, can bere-measured, and, if appropriate, an additional round of administrationcan be performed. In this way, multiple rounds of receptor/cell/liganddetection and antibody composition administration can be performed,e.g., until the disorder is brought under control.

It will also be appreciated that more than one antibody can be producedand/or used using the present methods. For example, combinations ofantibodies directed against different epitopes of NKG2A, againstdifferent combinations of NKG2A, CD94, or HLA-E, or against differentisoforms of any of the three proteins that may exist in any individualmay be used, as appropriate to obtain the ideal level of inhibition ofNKG2A stimulation or inhibition of NK cell activity, either generally orin any individual patient (e.g., following an analysis of theNKG2A-expressing cells in the patient to determine an appropriatetreatment regimen).

So long as a particular therapeutic approach is not known to bedetrimental to the patient's condition in itself, and does notsignificantly counteract the NKG2A antibody-treatment, its combinationwith the present invention is contemplated.

The present invention may also be used in combination with classicalapproaches, such as surgery, and the like. When one or more secondtherapeutic agents or approaches are used in combination with thepresent therapy, there is no requirement for the combined results to beadditive of the effects observed when each treatment is conductedseparately. Although at least additive effects are generally desirable,as long as the antibody compositions of this invention remain effectiveto inhibit or activate NK cells, the methods of this invention mayadditionally comprise the use of a second therapeutic agent or otherapproach. Also, there is no particular requirement for the combinedtreatment to exhibit synergistic effects, although this is certainlypossible and advantageous. The NKG2A antibody-based treatment mayprecede, or follow, the other treatment by, e.g., intervals ranging fromminutes to weeks and months. It also is envisioned that more than oneadministration of an anti-NKG2A composition of the invention will beutilized. The second therapeutic agent or other approach may beadministered interchangeably with the NKG2A antibody composition of thisinvention, on alternate days or weeks; or a cycle of anti-NKG2Atreatment may be given, followed by a cycle of the other agent therapyor approach. In any event, for methods that comprise the additional stepof administering a second therapeutic agent to a patient, all that isrequired is to deliver both the second therapeutic agent and theantibody of this invention in a combined amount effective to exert atherapeutically beneficial effect, irrespective of the times foradministration.

It will be appreciated that the present methods of administeringantibodies and compositions to patients can also be used to treatanimals, or to test the efficacy of any of the herein-described methodsor compositions in animal models for human diseases. Thus, the term“patient” as used herein means any warm-blooded animal, preferably amammal, more preferably a primate and most preferably a human.

Further aspects and advantages of this invention are disclosed in thefollowing experimental section, which should be regarded as illustrativeand not limiting the scope of this application.

EXAMPLES

Example 1—Killing of Autologous IDC is Mediated by a Subset ofCD94/NKG2A+KIR−NK Cells

Polyclonal NK cells cultured in the presence of exogenous IL-2 werepreviously shown to display strong cytolytic activity against iDC.Accordingly, in the present study, polyclonal NK cell populationsisolated from donors AM, AC and DB efficiently killed both autologousand allogeneic iDC. However, the cytolytic activity against autologousiDC could be incremented in the presence of appropriate anti-HLA class ImAb.

These data could be the consequence of the disruption of inhibitoryinteractions occurring between self HLA class I on DC and inhibitoryreceptors on NK cells. On the basis of these results, we formulated thehypothesis that only a fraction of the total NK cell pool displaysspontaneous cytotoxicity against iDC whereas the other NK cells do notbecause of effective inhibitory interactions between their receptors andHLA class I molecules. To analyze this possibility, a panel of NK cellclones isolated from donors AM, AC and DB were assessed for cytolyticactivity against autologous (and allogeneic) iDC. Consistent with ourhypothesis, only a fraction of NK cell clones lysed autologous iDC. Theother clones displayed either little or no cytotoxicity. Moreover, thepercentage of cytolytic clones was slightly increased when target cellswere represented by allogeneic iDC (see below).

To verify whether the inability of certain NK cell clones to lyse iDCreflected the interaction of their inhibitory NKR with HLA class Imolecules, these clones were analyzed for the ability to lyse autologousiDC either in the absence or in the presence of anti-HLA class I mAb(i.e. under conditions that disrupt the inhibitory interactions). On thebasis of the results of these experiments, NK cell clones were groupedinto three different functional categories and further analyzed for theexpression of HLA class I-specific inhibitory receptors including killerIg-like receptor (KIR)2DL, KIR3DL1 and CD94/NKG2A (i.e. the main MHCclass I-specific inhibitory receptors in humans).

The first group (group A) of NK clones was characterized by highspontaneous cytolytic activity against iDC. The magnitude of theircytolytic activity could not, or could only minimally, be increased inthe presence of anti-HLA class I mAb. These clones were ratherhomogeneous in terms of expression of inhibitory receptors as theyexpressed CD94/NKG2A but lacked KIR2DL and KIR3DL1, which react withself-HLA class I alleles. The second group of NK cell clones (group B)was also characterized by the capability of spontaneously killing iDC.However, at variance with group A clones, their cytotoxicity increasedin the presence of anti-HLA class I mAb. This suggested the occurrenceof inhibitory interactions that limited, but did not abrogate, theNK-cell mediated cytolysis. This group was also composed of CD94/NKG2A+clones and lacked KIR reactive with self-HLA class I alleles.Remarkably, the cytolytic activity of group B NK clones could also beincremented in the presence of anti-CD94 mAb thus indicating that the(partial) inhibition of cytotoxicity was indeed mediated by CD94/NKG2A.

NK clones belonging to the third group (group C) did not displaycytotoxicity against autologous iDC. However, in the presence ofanti-HLA class I mAb, iDC were efficiently lysed, suggesting theoccurrence of potent inhibitory interactions. These NK clones were moreheterogeneous regarding the expression of inhibitory receptors.Remarkably, virtually all NK clones expressing KIR2DL or KIR3DL1specific for self-HLA class I alleles were included in this group.Moreover, some of these clones were characterized by the expression of asingle KIR whereas others expressed multiple KIRs with differentspecificities. The reconstitution of cytolytic activity against iDCcould be obtained not only with anti-HLA class I mAb but also withanti-KIR mAb (see below).

Finally a minor fraction of group C NK cell clones was KIR−CD94/NKG2A+.Their cytotoxicity could be reconstituted by mAb-mediated blocking ofCD94 or by anti-HLA class I mAb. These data indicate that: (a) Not allNK cells are capable of killing autologous iDC (although all NK cellscould lyse iDC in the presence of anti-HLA class I mAb); (b) clonesdisplaying spontaneous cytolytic activity against iDC are restricted toan NK subset characterized by the CD94/NKG2A+KIR−surface phenotype(groups A and B); (c) clones expressing KIR2DL or KIR3DL1, which arespecific for self-HLA class I alleles, do not kill autologous iDC (groupC).

Some NK clones expressed both self-reactive KIR and CD94/NKG2A. In allinstances, they were confined to group C and their cytolytic activitycould be reconstituted both by anti-HLA class I and anti-KIR mAb,whereas anti-CD94 mAb had little or no effect. Finally it is worthmentioning that KIR+NKG2A−clones were found to display cytolyticactivity against iDC only in experiments in which iDC were derived fromallogeneic (KIR mismatched) individuals. In this case, KIR+NKG2A−cellsdisplay alloreactivity because the expressed KIRs fail to recognize HLAclass I alleles on allogeneic DC. The representative NK clone AM4(KIR3DL1+) was unable to kill autologous iDC (BW4+BW6−) whereas it lysedallogeneic, KIR mismatched (BW4−BW6+) iDC. Killing of autologous iDCcould be reconstituted in the presence of anti-HLA class I mAb whereaskilling of allogeneic iDC was not significantly modified.

Another example indicating the ability of KIR to distinguish betweenautologous and allogeneic, KIR-mismatched, iDC is provided by clone DB3,which co-expresses KIR2DL1 and KIR2DL2. This clone can be defined as“non-alloreactive” because, on the basis of its KIR phenotype, it shouldrecognize all different HLA-C alleles (both group 1 and group 2). Indeedthis clone did not kill autologous or allogeneic iDC whereas lysis ofboth targets could be efficiently reconstituted by anti-HLA class I mAb.Moreover, reconstitution of lysis was obtained by anti-KIR2DL2 mAbagainst autologous (CW1/CW3) iDC and by anti-KIR2DL1 mAb againstallogeneic (CW2/CW4) iDC. Finally, as expected, in the case ofNKG2A+KIR−clones no substantial difference existed in the ability tokill autologous or allogeneic iDC.

Example 2—the Susceptibility of IDC to NK-Mediated Cytotoxicity Reflectsthe Down-Modulation of HLA-E Class I Molecules

Previous studies demonstrated that iDC and mDC display remarkabledifferences in terms of HLA class I surface expression. Thus, by the useof mAb specific for a monomorphic determinant of HLA-A, B, C and Emolecules, it has been shown that DC undergoing maturation greatlyup-regulate their HLA class I expression at the cell surface. Moreover,the up-regulation of HLA class I represented a crucial mechanism bywhich mDC become resistant to NK-cell-mediated lysis.

To directly assess the expression of various HLA class I molecules oncells representative of different stages of DC maturation wecomparatively analyzed the expression of HLA-A, B, C and E on monocytes,iDC and mDC derived from the same individual. All HLA class I moleculeswere highly up-regulated in mDC as compared with iDC. Remarkably, theywere clearly down-regulated in iDC as compared with monocytes (i.e. theprecursors of iDC). Thus, it appears that the generation of iDC frommonocytes results not only in the acquisition (or up-regulation) ofnovel surface molecules (for example CD1a) and functional properties butalso in the loss (or down-regulation) of the expression of variousmolecules including CD14, and HLA-A, B, C and E molecules. This wouldsuggest that the degree of HLA class I down-regulation is tuned tolevels that allow iDC to become sensitive to lysis mediated by aparticular subset of NK cells (CD94/NKG2A+KIR−).

Along this line, because KIR+NK cells are unable to kill iDC, it isconceivable that the amount of HLA-B or HLAC molecules expressed by iDCis sufficient to generate KIR cross-linking and delivery of inhibitorysignals. On the other hand, the down-regulation of HLA-E would besufficient to enable a fraction of KIR−NKG2A+NK cells to kill iDC.Indeed it can be seen that HLA-E (as detected by the HLA-E-specific 3D12mAb) was almost undetectable in iDC whereas it was only partiallyre-expressed in mDC. However, in all instances, the HLA-E expression inmDC was lower as compared with monocytes or PBL derived from the sameindividual. Surprisingly, although HLA-A, B and C molecules wereexpressed by mDC at levels higher than by PHA blasts, the surfaceexpression of HLA-E was consistently lower in mDC than in PHA blasts. Inthis context, previous studies provided clear evidence that autologousPHA blasts are highly resistant to NK lysis independently of theKIR/NKG2A phenotype of the effector NK cells.

Example 3—A Small Fraction of NK Clones can Mediate Killing of MDC

Consistent with previous reports that polyclonal NK cells do notefficiently kill mDC, we show that most NK cell clones that lysed iDCdid not to kill mDC. Interestingly, however, mDC were lysed by a minorfraction of NK clones belonging to group A (i.e. those displayingspontaneous anti-iDC cytolytic activity that could not be increased byanti-HLA class I mAb). Lysis of autologous mDC was lower as comparedwith that of iDC and could be increased in the presence of anti-HLAclass I mAb. This suggests that the higher expression of HLA-E in mDC ascompared with iDC results in a more effective signaling via CD94/NKG2A(this is also suggested by the ability of anti-CD94 mAb to increasetheir lysis). Concerning group B NK clones (i.e. capable of killing iDCand whose lysis was incremented by anti-HLA class I mAb), they displayedno cytolytic activity again mDC; however, cytolytic activity could berevealed in the presence of anti-HLA class I or anti-CD94 mAb. Finallyclones belonging to group C (in most instances KIR+), which are unableto kill iDC, also failed to kill mDC. Cytotoxicity against mDC couldonly be detected upon mAb-mediated disruption of the interaction betweenHLA class I and KIR.

Example 4—Heterogeneity of KIR−NKG2A+NK Cells in the Ability to Kill DC

As illustrated above, NK cell clones belonging to group A and B arecharacterized by a homogeneous KIR−NKG2A+ surface phenotype whereasgroup C includes either KIR+NKG2A− or KIR−NKG2A+ clones, (or, lessfrequently, KIR+NKG2A+ clones). Assuming that the negative signaling viaKIR is more effective than that via NKG2A (either because of anintrinsic difference in their signaling capability or because of thedifferent availability of the specific HLA class I ligands on DC) itshould be clarified why KIR−NKG2A+ cells are detectable in all threegroups of NK clones. Since the cytolytic activity of a given NK cellclone is the result of a balance between inhibitory (KIR, NKG2A) andtriggering (NCR, NKG2D) receptors, we analyzed the levels of expressionof these molecules in the different groups of NK clones. In particular,we focused our attention on the expression of NKG2A and of NKp30 (i.e.the triggering NCR that plays a predominant role in the induction ofNK-cell-mediated lysis of iDC and mDC).

First, the NKG2A+KIR−clones belonging to group A, B and C were evaluatedfor the level of NKG2A surface expression. NK clones belonging to groupC expressed very high levels of NKG2A as compared with groups A and B.Moreover, group A clones were characterized by a lower expression ofNKG2A as compared with group B clones. These data suggest the existenceof an inverse correlation between the levels of NKG2A expression and theability to kill iDC (and mDC). The low amounts of HLA-E moleculesexpressed in iDC may be differentially sensed by NK cells expressinghigh or low levels of NKG2A whereas mDC (expressing higher levels ofHLA-E) are susceptible to lysis only by NK clones characterized by verylow NKG2A surface density. Regarding the expression of NKp30, this wascomparable in most NKG2A+ clones analyzed. Consistent with these data,their ability to kill iDC in the presence of anti-HLA class I mAb (i.e.in the absence of inhibitory interactions) did not show significantdifferences.

Discussion.

Heterogeneity exists even among NKG2A+KIR−cells in the magnitude ofcytolytic responses. This appears to inversely correlate with thesurface density of NKG2A. Accordingly, NK clones expressing low levelsof NKG2A (group A) lysed both iDC and mDC whereas those expressinghigher levels of NKG2A killed only iDC or, in a few cases, (NKG2Abright)failed to kill both iDC and mDC.

Notably, we also show that the surface expression of HLA-E is sharplyreduced in iDC as compared with monocytes whereas it is partiallyrecovered in mDC. On the contrary, the reduced cell surface levels ofHLA-B and HLA-C in iDC are still sufficient to effectively engageKIR3DL1 or KIR2DL.

An unexpected finding was the identification of a small subset of NKcell clones belonging to group A (5-10%) that were capable of killingautologous mDC. These NK clones do not express self-reactive KIR and arecharacterized by low levels of NKG2A. This allows these NK cells toreadily sense the down-regulation of HLA-E on target cells as comparedwith NK cells expressing higher levels of NKG2A. Accordingly noincreases of the cytolytic activity of NKG2A low NK cells against iDCoccurred in the presence of anti-HLA class I mAb. On the other hand, inthe case of mDC (expressing higher levels of HLA-E), addition ofanti-HLA class I mAb resulted in an increase of cytolytic activity,indicating that, provided a sufficient level of receptor-ligandinteraction, NKG2A molecules expressed by group A clones can inhibitlysis. It is conceivable that in mDC some degree of heterogeneity mightexist in the expression of HLA-E and, possibly, of ligand(s) of NKp30.Given the ability of a fraction of NK cells to discriminate betweencells that express different amounts of HLA-E, it is possible that amongmDC only some may express a surface density of HLA-E sufficient toconfer resistance to this particular subset of NK cells.

Example 5—Z270 Anti-NKG2A mAb Increases Lytic Activity of NK Cell LinesTowards Immature Dendritic Cells

Z270 is a mouse IgG1 monoclonal antibody against NKG2A. Because Z270 isa mouse antibody, it does not bind to human Fc receptors and thus actsas an activating antibody of this invention in human cell systems or inany system that lacks cells bearing mouse Fc receptors. In contrast, ina system comprising cells bearing a mouse Fc receptor, Z270 is aninhibitory antibody of this invention, due to the fact that its IgG1constant region binds to such Fc receptors.

Human NK cell clones expressing NKG2A and immature dendritic cells(plasmacytoid dendritic cells or myeloid dendritic cells) were generatedusing standard methods. The lytic activity of the resulting human NKcell clones BH3, BH18 and BH34 was tested on autologous immaturedendritic cells. Lytic activity of each of these clones against the iDCwas tested in parallel in the absence or presence of monoclonalantibodies to CD94 (IgM) and to NKG2A (Z270, IgG1). For comparison,lytic activity in the presence of an anti-HLA class I antibody and acontrol IgG1 (anti-2B4 antibody) was also tested.

As shown in Table 1 below, NK clones showed little lysis of iDC in theabsence of antibody or in the presence of control antibody anti-2B4 mAb.However, killing of the autologous iDC could be reconstituted in thepresence of either anti-CD94, anti-NKG2A mAb Z270 or anti-HLA class ImAb. This result demonstrates that interference with NKG2A functionreconstitutes NK cell lysis of iDC. It also demonstrates that the NKG2Abinding region of monoclonal Z270 is capable of blocking NKG2A'sinhibitory function.

TABLE 1 lysis of autologous iDC NK Clone BH3 BH18 BH34 control lysis 257382 318 anti CD94 1341 2455 2376 anti-NKG2A (Z270) 984 1977 2108anti-HLA class I 1397 2603 2498 anti-2B4 (control IgG1) 236 353 292

Example 6—Reconstitution of Autologous Target Cell Lysis UsingAnti-NKG2A Antibodies

The cytolytic activity of human NK bulk cells against autologous PHAblast target cells expressing HLA-E in the absence of antibody or thepresence of mAbZ199, or mAbZ270, was tested. Cytolytic activity wasassessed by a standard 4 hour ⁵¹Cr release assay. All target cells wereused at 3000 cells per well in microtitration plate. The number of NKcells was varied to produce effector/target ratios of between 0.01-100,as indicated in FIG. 1.

In the absence of antibody, NK cells displayed little if any cytolyticactivity against target cells expressing HLA-E. However, in the presenceof the anti-NKG2A antibody Z270 (having a mIgG1 constant region) or Z199(having a mIgG2b constant region) NK clones became unable to recognizetheir HLA-E ligands and displayed strong cytolytic activity against thePHA blast targets. Z270 has a murine IgG1 constant region and Z199 has amurine IgG2b constant region. Neither of those antibodies cansignificantly bind to human Fc receptors.

Similarly, inhibition of NK bulk cell killing of HLA-E positiveautologous PHA blast cells could be efficiently reversed by the use of aZ270 F(ab′)2 fragment (FIG. 2), an anti-KIR mAb DF200 or pan2D whichblock signaling through KIR2DL1 and KIR2DL2,3, or by antibody W6/32.Also, under the conditions tested (E/T ratio=1, 50 μg/ml mAb) PHA blastcells were not killed by NK bulk cells, but this inhibition could bereversed by the use of either Z270 mAb or Z270 Fab fragment.

Example 7—Materials and Methods

mAb.

The following mAb, produced in our laboratory, were used in this study:JT3A (IgG2a, anti-CD3), AZ20 and F252 (IgG1 and IgM, respectively,anti-NKp30), c127 (IgG1, anti-CD16), c218 (IgG1, anti-CD56), EB6b (IgG1,anti-KIR2DL1 and KIR2D S1), GL183 (IgG1, anti-KIR2DL2 KIR2DL3 andKIR2DS2), FES172 (IgG2a, anti-KIR2DS4), Z27 (IgG1, anti-KIR3DL1), XA185(IgG1, anti-CD94), Z199, Z270 (IgG2b, anti-NKG2A), A6-136 (IgM, anti-HLAclass I), 131 (IgG1, anti-HLA-A alleles including A3, All and A24) andE59/53 (IgG2a, anti-HLA-A) [Ciccone et al, (1990) PNAS USA 87:9794-9797;Pende et al, (1998) J Immunol. 28:2384-2394]. The mAb F4/326 (IgG,anti-HLA-C) [Marsh et al, (1990) Tissue Antigens 36: 180-186], 116-5-28(IgG2a, anti-HLA-Bw4 alleles) and 126-39 (IgG3, anti-HLA-Bw6 alleles)were kindly provided by Dr K. Gelsthorpe (Sheffield, GB) (XIIInternational HLA Workshop) and 3D12 (IgG1, anti-HLA-E) [Lee et al.(1998) J. Immunol. 160:4951-4960] was kindly provided by Dr. DanielGeraghty (Fred Hutchinson Cancer Research Center, Seattle, Wash.).

Anti-CD1a (IgG1-PE), anti-CD14 (IgG2a), anti-CD83 (IgG2b) and anti-CD86(IgG2b-PE) were purchased from Immunotech (Marseille, France). D1.12(IgG2a, anti-HLA-DR) mAb was provided by Dr R. S. Accolla (Pavia,Italy). HP2.6 (IgG2a, anti-CD4) mAb was provided by Dr P. Sanchez-Madrid(Madrid, Spain).

Generation of polyclonal or clonal NK cell populations. To obtain PBL,PBMC were isolated on Ficoll-Hypaque gradients and depleted ofplastic-adherent cells. Enriched NK cells were isolated by incubatingPBL with anti-CD3 (JT3A), anti-CD4 (HP2.6) and anti-HLA-DR (D1.12) mAb(30 min at 4° C.) followed by goat anti-mouse coated Dynabeads (Dynal,Oslo, Norway) (30 min at 4° C.) and immunomagnetic depletion.CD3-CD4-HLA-DR-cells were cultured on irradiated feeder cells in thepresence of 100 U/ml rIL-2 (Proleukin, Chiron Corp., Emeryville, Calif.)and 1.5 ng/ml PHA (Gibco Ltd, Paisley, GB) to obtain polyclonal NK cellpopulations or, after limiting dilution, NK cell clones as previouslydescribed.

Generation of DC. PBMC were derived from healthy donors and plasticadherent cells were cultured in the presence of IL-4 and GMCSF(Peprotech, London, GB) at a final concentration of 20 ng/ml and 50ng/ml, respectively. After 6 days of culture, cells were characterizedby the CD14−CD1a+CD83−phenotype corresponding to iDC. To generateCD14−CD1a+CD83+CD86+ mDC, iDC were stimulated for 2 days with LPS(Sigma-Aldrich, St. Louis, Mich.) at a final concentration of 1 ug/ml.

Flow cytofluorimetric analysis and cytolytic activity. For one- ortwo-color cytofluorimetric analysis (FACSCalibur, Becton Dickinson andCo., Mountain View, Calif.), cells were stained with the appropriate mAbfollowed by PE- or FITC-conjugated isotype-specific goat anti-mousesecond reagent (Southern Biotechnology Associated, Birmingham).Polyclonal and clonal NK cell populations were tested for cytolyticactivity in a 4-h [510]-release assay against either autologous orheterologous DC. The concentrations of the various mAb added were 10ug/ml for masking experiments. The E:T ratios are indicated in the text.

Example 8—Chimerization of Z270 Heavy and Light Chain Variable Regions

Frozen cell pellets of mouse hybridoma line, Z270, were thawed andprocessed using the RNeasy Midi Kit (Qiagen cat. No. 75142) to isolate71 μg of total RNA. About 5 micrograms of Z270 RNA was subjected toreverse transcription to produce Z270 cDNA using the AmershamBiosciences 1st strand synthesis kit (Amersham Biosciences, Cat. No.27-9261-01). Immunoglobulin heavy chain variable region (VH) cDNA wasamplified by PCR using a number of different IgH primers in combinationwith a constant region primer in order to determine which primer pairwas the most suitable for PCR. Similarly, immunoglobulin kappa chainvariable region (VK) was amplified using multiple IgK primers incombination with a kappa constant region primer.

Suitable primers for each of the heavy and light chain variable regionswere identified and ligated separately into pCR2.1®-TOPO Vectors® fortransformation into E. coli TPO10 bacteria, amplification and sequencing(using the BigDye® Terminator v3.0 Cycle Sequencing Ready Reaction Kit(ABI). The DNA sequence of the heavy chain variable region (Z270 VH) andthe corresponding amino acid sequence are set forth in SEQ ID NO:1 andSEQ ID NO:2, respectively. The DNA sequence of the light chain variableregion (Z270 VK) and the corresponding amino acid sequence are set forthin SEQ ID NO:3 and SEQ ID NO:4, respectively.

Chimerization of Z270 VK involved introducing via the appropriateprimers and PCR, a Hind III restriction site, a Kozak translationinitiation site and the K2A/RFT2 kappa leader sequence at the 5′ end anda splice donor site and Bam HI restriction site at the 3′ end of theZ270 VK DNA sequence. The resulting PCR product was cloned into a vectorencoding the constant region of the human kappa light chain so as toencode a full-length chimeric light chain containing the variable regionof the Z270 light chain. The DNA sequence of the resulting chZ270VK andthe corresponding amino acid sequence are set forth in SEQ ID NO:5 andSEQ ID NO:6, respectively.

Chimerization of Z270 VH involved introducing via the appropriateprimers and PCR, a Hind III restriction site, a Kozak translationinitiation site and the A003 leader sequence at the 5′ end and the 5′end of the gamma1 C region including a natural Apa I restriction site atthe 3′ end of the Z270 VH DNA sequence. The resulting PCR product wascloned into a vector encoding the constant region of the human IgG1heavy chain so as to encode a full-length chimeric IgG1 heavy chaincontaining the variable region of the Z270 heavy chain. The DNA sequenceof the resulting chZ270VH and the corresponding amino acid sequence areset forth in SEQ ID NO:7 and SEQ ID NO:8, respectively.

The resulting heavy and light chain containing plasmids weresimultaneously electroporated into COS 7 cells which expressed theresulting human IgG1-kappa chimersation construct of Z270.

Example 9—Generation of New mAbs

mAbs were generated by immunizing 5 week old Balb C mice NK clone SA260(CD94bright). After different cell fusions, the mAbs Z199 and Z270 werefirst selected as described in Moretta et al., (1994) J. Exp. Med.180:545. Analysis of resting or activated NK cell populations for thedistribution of the CD94 molecules was performed using one or two-colorfluorescence cytofluorometric analysis as described in Moretta et al.(1994).

Positive monoclonal antibodies were further screened for their abilityto reconstitute lysis by NK clones. The cytolytic activity of NK cloneswas assessed by a standard 4 hour ⁵¹Cr release assay in which effectorNK cells were tested against the P815 mouse cell line or the C1R humancell line transfected or not with various HLA class I genes. Othertarget cells used in these studies were represented by the humanHLA-class I-LCL 721.221 cell line either untransfected or transfectedwith various HLA classes as described in Sivori et al. (1996) Eur. J.Immunol. 26: 2487-2492.

Example 10—Purification of PBLs and Generation of Polyclonal or ClonalNK Cell Lines

PBLs are obtained from healthy donors by Ficoll Hypaque gradients anddepletion of plastic adherent cells. To obtain enriched NK cells, PBLsare incubated with anti CD3, anti CD4 and anti HLA-DR mAbs (30 minutesat 4° C.), followed by goat anti mouse magnetic beads (Dynal) (30minutes at 4° C.) and immunomagnetic selection by methods known in theart (Pende et al., 1999). CD3⁻, CD4⁻, DR⁻ cells are cultivated onirradiated feeder cells and 100 U/ml Interleukin 2 (Proleukin, ChironCorporation) and 1.5 ng/ml Phytohemagglutinin A (Gibco BRL) to obtainpolyclonal NK cell populations. NK cells are cloned by limiting dilutionand clones of NK cells are characterized by flow cytometry forexpression of cell surface receptors.

Example 11—Staining of Whole Blood from Monkeys to Identify IndividualExpression of Receptors Binding Anti-NKG2A mAb Materials

Monkey blood: blood for rhesus and cynomolgus monkeys was purchased atCentre de Primatologie, ULP, Strasbourg. Monkey blood for Baboons waspurchased at Centre de Primatologie, CNRS, Station Rousset. Monkey bloodwas collected in “vacutainer” tube containing EDTA or sodium citrate.Blood was processed within the 24 hours following collection and kept atroom temperature.

Antibodies: FITC-CD3, -CD4, -CD14, -CD20, and CyCr-CD45 are from BDPharmingen, PC7-CD16 was obtained from Beckman Coulter; all these clonesare cross-reacting with monkey PBMCs. PE-GaM (Goat F(ab′)2 fragmentanti-Mouse IgG (H+L)-PE), and OptiLyse® C. were purchased from BeckmanCoulter. Anti-NKG2a mAb (clone Z270, mouse IgG1) used at 1 μg/ml.

Other reagents: PBS (1×) obtained from Gibco Invitrogen; mouse serumfrom NMRI mouse from Janvier; Formaldehyde 37% from Sigma.

Methods:

Cell staining was carried out according to the following protocol:

-   -   100 μl of blood+10 μl of 10× purified mAb    -   Incubate with agitation 30 min at RT    -   Wash with 3 ml PBS (1400 RPM 10 min RT)    -   Add 100 μl PE-GaM or PE-GaH, 1:200 final, vortex    -   Incubate with agitation 30 min at RT    -   Wash with 3 ml PBS (1400 RPM 10 min RT)    -   Add 50 μl of 20% mouse serum, vortex and incubate 10 min    -   Add 30 μl to 60 μl of FITC-CD3,(-CD4,-CD14,-CD20), PC7-CD16,        CyCr-CD45 mixture or 10 μl of each corresponding isotypic        control    -   Incubate with agitation 30 min at RT    -   Add 500 μl OptiLyse® C., vortex and incubate 10 min    -   Add 500 μl PBS, vortex and incubate 10 min    -   Wash with 3 ml PBS (1400 RPM 10 min RT)    -   Resuspend cell pellet in 300 μl PBS+0.2% Formaldehyde.        Flow cytometry was carried out according to the following        protocol:    -   Samples are run on a XL/MCL cytometer (Beckman Coulter).        Acquisition and analysis are performed with EXPO™ 32 v1.2        software (Beckman Coulter).    -   Analysis is focused on lymphocytes identified by their FSC and        SSC features.    -   Analysis of the T cell or NK cell compartments:

T cells=CD3⁺ lymphocytes are defined as the positive cells of theanti-CD3 staining histogram gated on Ly.

NK cells=CD3⁻CD56⁺ lymphocytes corresponds to the CD3⁻CD56⁺ gate in theCD3/CD56 dot plot (upper left part of the quadrant).

Results

Binding of NKG2A monoclonal antibody Z270 to rhesus monkeys, cynomolgusmonkeys and baboons was assessed. Cynomolgus monkey bulk NK cells (day16, 300 uml were incubated 30 min at 4° C. with mAb (1 μg/ml), washedand labelled 20 min at 4° C. with PE-GaM. FIG. 1 shows binding tocynomolgus monkey NK cells, as well as IgG1 and anti-CD16 bindingdemonstrating that Z270 binds to cynomolgus monkey NK cells. Macacamulatta (rhesus monkey) NK cells (from whole blood) were incubated withmAb, washed and labelled with PE-GaM. Results, shown in Table 2,demonstrate binding of clone Z270 to the rhesus monkey NK cells.Finally, baboon NK cells (from whole blood) were incubated with mAb,washed and labelled with PE-GaM. Results, shown in Table 3, demonstratebinding of clone Z270 to the baboon NK cells.

Example 12—Staining of Whole Blood from Monkeys to Identify IndividualExpression of Receptors Binding Anti-NKG2A mAb Materials

Monkey blood from rhesus and cynomolgus monkeys was collected in a tubecontaining EDTA or sodium citrate. Antibodies: FITC-CD3, -CD4,-CD14,-CD20, and CyCr-CD45 are from BD Pharmingen, PC7-CD16 was obtainedfrom Beckman Coulter; all these clones are cross-reacting with monkeyPBMCs. PE-GaM (Goat F(ab′)2 fragment anti-Mouse IgG (H+L)-PE), andOptiLyse® C. were purchased from Beckman Coulter. Other reagents: PBS(1×) obtained from Gibco Invitrogen; Formaldehyde 37% from Sigma.

Methods:

Cell staining was carried out according to the following protocol:

100 μl whole blood (EDTA)+11 μl mAb solution, Z270 or Z199 (10 μg/ml) orisotype control, incubated for 30 min at RT

Wash with PBS, add 100 μl PE- or FITC GaM (1/200 final) and leave for 30min at RT

Wash with PBS, add 50 μl mouse serum 20%, add 60 μl containingFITC-anti-CD3,-CD4, -CD14, -CD20, CyCr-CD45, PC7-CD16 and leave for 30min at RT

Add 500 μl of optilyseC, leave for 10 min at RT

Add 500 μl of PBS and leave for 10 min at RT

Wash with PBS and with 0.2% Formaldehyde.

-   -   Analysis focus on CD45^(bright) small cells (CD45/SSC) then on        CD16⁺CD3⁻CD4⁻CD14⁻CD20⁻ cells.

Results

Binding of NKG2A monoclonal antibodies Z270 and Z199 to rhesus monkey NKcells and cynomolgus monkey NK cells was assessed and compared.Cynomolgus monkey bulk NK cells (day 16, 300 μl were incubated 30 min at4° C. with mAb (1 μg/ml), washed and labelled 20 min at 4° C. withPE-GaM. Table 4 shows binding of both Z199 and Z270 to cynomolgus monkeyNK cells, as well as IgG1 and anti-CD16 binding demonstrating that bothZ199 and Z270 bind to cynomolgus monkey NK cells. Macaca mulatta (rhesusmonkey) NK cells (from whole blood) were incubated with mAb, washed andlabelled with PE-GaM. Results, shown in Table 5, demonstrate binding ofboth clones Z199 and Z270 to the rhesus monkey NK cells.

It has further been observed (Biassoni et al, (2005) J. Immunol. 174:5695-5705, see FIGS. 5 and 6) that Z199 binds cynomolgus monkey NKG2C inaddition to NKG2A, and moreover that this mAb results in increase inlysis of P815 target cells in a redirected killing assay. The latterincrease in lysis is the opposite observed with human NK cells and isopposite that which would be expected for an inhibitor receptor NKG2A.Thus, while not wishing to be bound by theory present inventors proposethat Z199 acts through the activatory receptor NKG2C in cynomolgusmonkeys. Z270 also binds cynomolgus monkey cells and results in anincrease in lysis of P815 target cells in a redirected killing assaysuggesting that Z270 also recognizes NKG2C in the cynomolgus monkey.

The level of binding however of the two mAbs on the same species(cynomolgus for example) is very different both in terms of percentageof cells stained and intensity of fluorescence. This means that the twoantibodies bind differently to NKG2A epitopes.

TABLE 2 weight m IgG1 Z270 mulatta sex (kg) % N % % MFI+ CH256 F 8.4 3.50.8 78.1 6.5 *8703 F 7.1 2.4 0.4 56.1 5.3 P9215 F 5.85 4.4 1.4 89.7 12.9RU925 F 1 5.9 0.4 95.2 15 201 M 14.6 14.4 1.3 95.7 8.1 PM021 M 3.7 5 0.861.7 5.7 MM031 M 2.25 1.8 0.4 88.1 10 N0401 M 1.75 2.6 0.5 87.1 8.99N0404 M 1.25 1.7 0.6 86.3 9 Mean 0.7 83 9.1 SD 0.4 12.3 3.2 n 9 9 9Range 61.7-95.7 5.3-12.9

TABLE 3 m IgG1 Z270 % tot. tot. Baboon sex birth NK % MFI % MFI K05 FJan. 1, 1994 6.7 34 0.9 K938A F Dec. 29, 1998 1.3 0.3 0.3 8.7 0.9 O22V FJul. 7, 1998 2.9 0.5 0.2 0.4 0.2 V992 F Jan. 31, 1999 5.1 0.6 0.3 41.2 1V997 F Mar. 29, 1999 5.5 0.7 0.2 32.3 0.8 V999 F Apr. 4, 1999 5.2 0.30.2 2.3 0.3 V9912 F May 7, 1999 4.7 0.2 0.2 12 1.4 V9914 F May 17, 19993.8 0.1 0.3 10.9 1 V9926 F Jun. 13, 1999 5.4 0.5 0.2 2.7 0.3 V9929 FNov. 7, 1999 7.9 0.3 0.2 0.9 0.2 PA977 M Dec. 3, 1997 2.8 0.9 1.1 11.41.6 PA983 M Aug. 13, 1998 4.5 0.1 0.7 24.6 2 V942A M Jun. 10, 1999 0.81.7 1 14.3 1.6 V857C M Oct. 29, 2000 7.2 0.8 1.4 79.7 9 V861B M Jan. 7,2000 0.8 0.2 0.6 57.1 2.5 V914B M Feb. 19, 2000 2 0.4 1.1 0.8 1.3 V918CM Feb. 19, 2000 4.2 0.3 1.1 79.7 9 V9812 M Jul. 6, 1998 5.6 1.3 1.2 78.16.2 V989 M Jun. 1, 1998 1.5 1.2 1.2 12.4 2 V9920 M Aug. 26, 1999 3.7 0.70.8 14.2 1.6 Mean 4.1 30.3 SD 2.1 27.35 Range 0.8 to 7.9 2.3 to 79.7 n20 17

TABLE 4 Analysis of NK cell subsets from peripheral rhesus monkey wholeblood IgG1 Z270 IgG2b Z199 Weight % NK % % MFI % % MFI Name (kg) MeanMFI NK⁺ MFI NK⁺ NK⁺ MFI NK⁺ MFI NK⁺ NK⁺ 34459 9.6 5.81 5.88 6.07 6.066.44 6.1 0.76 1.4 2.7 40.8 5.6 0.7 1.2 63.8 96.2 66.3 31828 7.9 9.9 9.959.09 9.54 9.44 9.6 0.65 0.4 4.3 88.9 4.6 0.7 0.5 101.0 99.8 101.0 O96710.4 13.2 14.1 14 13.5 13.5 13.7 0.67 0.5 2.7 40.8 5.6 0.7 0.5 62.3 84.873.4 R00093 6.2 4.93 5.22 5.25 5.38 5.09 5.2 0.68 1.0 2.5 40.9 4.5 0.60.4 81.9 97.9 83.6 R00013 7.6 6.2 7.36 7.34 7.28 6.21 6.9 0.66 0.3 1.412.4 3.8 0.6 0.2 38.8 97.8 39.7 R00085 7.6 7.63 7.59 7.87 7.13 7.88 7.60.7 0.9 3.0 49.3 4.7 0.7 0.3 68.4 91.9 74.4 R00055 6.8 8.54 8.04 8.018.2 0.7 0.6 4.0 65.8 5.3 0.6 0.9 R99273 9.4 10.1 9.85 8.8 9.8 9.27 9.60.54 0.5 2.0 49.5 2.9 0.4 0.6 32.7 98.0 33.4 R00073 5.6 8.43 7.8 7.317.29 7.72 7.7 0.4 0.5 2.2 84.5 2.4 0.4 0.39 31.6 99.1 31.9 R00073 6.15.65 5.56 5.45 5.69 4.28 5.3 0.59 0.7 3.3 84.8 3.7 0.3 0.3 31.9 98.032.6 R00077 7.2 11.2 10.9 11.9 10 7.9 10.4 0.41 0.4 5.0 80.2 6.1 0.4 0.530.4 97.1 31.3 R00025 6.3 6.91 6.57 10.3 9.87 9.27 8.6 0.45 0.7 2.2 79.22.5 0.4 0.4 30.0 97.3 30.9 R00041 7.7 9.72 9.71 9.16 9.25 8.49 9.3 0.480.9 2.9 77.4 3.5 0.4 0.3 33.1 89.6 36.9 R00099 5.8 6.14 5.8 6.12 5.455.39 5.8 0.56 1.2 2.5 58.5 3.6 0.5 0.3 31.1 97.6 31.8 R00037 5.1 4.755.01 5.01 4.7 3.88 4.7 0.5 0.6 1.5 50.1 1.9 0.5 0.3 26.7 96.9 27.5R00023 5.8 11.8 11 10.7 8.46 11.3 10.6 0.5 0.3 4.4 90.9 4.7 0.3 0.6 34.096.4 35.3 R00101 6.1 12.1 11.6 13 12.1 11.5 12.1 0.58 0.5 6.0 82.5 7.10.5 0.4 37.1 98.7 37.6 R00061 5.7 5.96 5.26 5.62 5.6 5.59 5.6 0.5 0.55.4 59.4 8.5 0.6 0.2 1.6 40.7 2.4 R00007 6.5 18.4 17.5 16.6 18 18.8 17.90.52 1.5 3.8 67.9 4.9 0.4 0.7 34.9 99.6 35.0 Mean 8.7 0.6 0.7 3.4 63.44.3 0.5 0.5 29.6 93.2 30.6 SD 3.3 0.1 0.4 1.5 21.3 2.0 0.1 0.3 9.2 13.69.3

TABLE 5 Analysis of NK cell subsets from peripheral cynomolgus monkeywhole blood IgG1 Z270 IgG2b Z199 % NK % % MFI % % MFI Kg Mean MFI NK⁺MFI NK⁺ NK⁺ MFI NK⁺ MFI NK⁺ NK⁺ 1221 9.1 14.9 13.7 15 14.4 14.3 14.40.53 0.6 4.6 57.1 7.1 0.8 1.3 105.0 96.7 109.0 M859 9 7.76 8.8 8.18 8.838.13 8.3 0.51 0.2 4.6 74.7 5.7 0.6 0.2 144.0 95.1 152.0 R390 3.6 4.113.77 3.61 2.84 3.73 3.6 0.39 0.2 3.6 43.9 6.9 0.5 0.2 32.3 99.0 32.6T270 3.6 16.4 16.1 17.8 18.8 17.3 0.54 0.2 1.1 4.5 3.4 0.6 0.2 113.097.7 116.0 T788 3.3 5.55 5.22 5.41 4.95 5.63 5.4 0.5 0.3 1.8 18.8 4.60.6 0.4 123.0 97.0 126.0 AK565 3.9 10.7 10.4 9.82 9.98 9.59 10.1 0.660.6 3.4 41.7 6.7 0.6 0.3 28.2 90.7 31.0 AK729 3 5.61 5.78 5.75 5.75 5.875.8 0.6 0.3 1.3 9.7 4.7 0.6 0.3 37.4 99.4 37.7 AL210 3.3 4.68 4.63 4.855 4.8 0.65 0.4 3.3 54.4 5.0 0.7 0.3 126.0 92.7 136.0 AL303 2.8 19.9 19.119.5 18.9 18.2 19.1 0.63 0.13 1.9 24.2 3.7 0.7 0.14 129.0 99.1 130.0AL389 5.2 7.53 7.96 8.23 7.75 6.49 7.6 0.63 0.3 5.3 78.7 6.3 0.8 0.4223.0 95.5 234.0 Mean 9.6 0.6 0.3 3.1 40.8 5.4 0.7 0.4 106.1 96.3 110.4SD 5.5 0.1 0.2 1.5 26.0 1.3 0.1 0.3 60.2 2.9 63.2 N 10

All publications and patent applications cited in this specification areherein incorporated by reference in their entireties as if eachindividual publication or patent application were specifically andindividually indicated to be incorporated by reference.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it will be readily apparent to one of ordinary skill inthe art in light of the teachings of this invention that certain changesand modifications may be made thereto without departing from the spiritor scope of the appended claims.

We claim:
 1. A monoclonal antibody or a fragment thereof characterizedby: a) specifically binding to NKG2A and not specifically binding toNKG2C or NKG2E; b) a human constant region that does not substantiallybind human FcγIIIa receptor (CD16); and c) when bound to NKG2A on ahuman NK cell, causing said NK cell to lyse a target human cell bearingHLA-E on the target cell surface, when said target cell comes intocontact with said NK cell.
 2. A composition comprising: a) an effectiveamount of a monoclonal antibody or a fragment thereof according to claim1; and b) a pharmaceutically acceptable carrier or excipient.
 3. Amethod of reconstituting NK cell-mediated lysis of a target cell in apopulation comprising a NK cell and said target cell, wherein said NKcell is characterized by NKG2A on its surface, and said target cell ischaracterized by the presence of HLA-E on its surface, said methodcomprising the step of contacting said NK cell with a monoclonalantibody or a fragment thereof according to claim
 1. 4. The methodaccording to claim 3, wherein said NK cell is a human cell and saidtarget cell is a human cell selected from a dendritic cell, a cancercell, a virally infected cell.
 5. A method of treating a cancer in apatient, wherein said cancer is characterized by the presence of acancer cell expressing HLA-E on its cell surface, said method comprisingthe step of administering to said patient a composition according toclaim
 2. 6. The method according to claim 5, comprising the additionalstep of administering to said patient a second therapeutic agentselected from: an anticancer agent or an antiemetic, wherein said secondtherapeutic agent is administered either as a separate dosage form or aspart of said composition.
 7. The method according to claim 5, whereinthe cancer is a cancer of the bladder, breast, colon, kidney, liver,lung, ovary, prostate, pancreas, stomach, cervix, thyroid and skin,including squamous cell carcinoma.
 8. The method according to claim 5,wherein the cancer is a hematopoietic tumor of lymphoid lineage.
 9. Amethod of treating a viral disease in a patient, wherein said viraldisease is characterized by the presence of a virally-infected cellexpressing HLA-E on its cell surface, said method comprising the step ofadministering to said patient a composition according to claim
 2. 10.The method according to claim 9, comprising the addition step ofadministering to said patient an antiviral agent, wherein said antiviralagent is administered either as a separate dosage form or as part ofsaid composition.
 11. A method of improving the engraftment ofhematopoietic cells in a patient, said method comprising the step ofadministering to said patient a composition according to claim
 2. 12.The method according to claim 11, comprising the additional step ofadministering to said patient a second therapeutic agent selected froman anticancer agent, or a hematopoietic growth factor, wherein saidsecond therapeutic agent is administered either as a separate dosageform or as part of said composition.
 13. The method according to claim11, wherein said patient is suffering from leukemia.